Interrail & Eurail train reservations

On this page I explain...

which operators are covered by Interrail/Eurail;

which trains require a reservation and which don't;

the cost of reservations;

how to make reservations.

Don't expect train ticket websites to sell passholder reservations, most don't. But you can usually make passholder reservations online if you know which website to use. Select the country where a train starts, look for that specific operator, route & train type and I'll tell you how.

Prices are per person per journey. Children (even with a free pass) pay the same reservation fee as adults. You can check these prices at www.eurail.com or www.interrail.eu. And remember, making reservations is totally separate from using the pass.

Incidentally, Eurail & Interrail passes are identical in terms of the trains/operators they cover and reservation fees. Last updated March 2025.

Select the country where the train starts

Austria

What's covered?

Interrail & Eurail passes give unlimited travel on Austrian Federal Railways (ÖBB), www.oebb.at.

That includes all local & mainline trains run by ÖBB and (if you've a global pass) international trains to or from neighbouring countries run jointly by ÖBB & the national railways in those countries. That includes railjets and nightjet sleeper trains.
Passes also give unlimited travel in standard (2nd) class on competing Westbahn trains between Vienna, Linz, Salzburg & Munich.
Passes give unlimited travel on privately-run Regiojet trains between Vienna & Prague, Vienna & Budapest, seat reservation required.
Passes give unlimited travel on Micotra trains between Villach & Tarvisio in Italy.
Passes give unlimited travel on Raaberbahn trains between Vienna/Graz & parts of Hungary.

Help with train times

For train times within Austria see www.oebb.at

See international train times & routes from Vienna

See international train times & routes from Salzburg

See international train times & routes from Innsbruck

Using a pass within Austria

ÖBB (Austrian Railways) trains

Using a railpass in Austria is easy as reservation is optional not mandatory on almost all Austrian Railways (ÖBB) domestic daytime trains, and there are no supplements to pay, even on railjet trains. So you can simply hop on any train, find an empty seat and show your pass when asked.

You can make a seat-only booking online for €3 per seat at the ÖBB website using Method 2, see the instructions here.
Westbahn trains

As well as ÖBB, you can also use competing Westbahn trains between Vienna, Linz & Salzburg. These give free travel in standard (2nd) class for holders of both classes of pass, reservation optional. If you have a 1st class pass, you can use Standard class for free or pay for an upgrade to Westbahn's Comfort class or First class.

You can reserve a seat in Standard class for €4.90 or pay for a €9.90 upgrade to Comfort or €34.90 upgrade to First with reservation included.

Go to www.westbahn.at, change DE to EN top right for English and click Reservations.

Nightjet sleeper train from Vienna to Bregenz: See passholder prices.
Passholder reservations for Nightjet sleeper trains can be made online at the ÖBB website using Method 1, see the instructions below.

Austria ► Belgium

Nightjet sleeper: Vienna to Brussels by Nightjet sleeper train: See passholder prices.
Passholder reservations for Nightjet sleeper trains can be made online at the ÖBB website using Method 1, see the instructions below.

Austria ► France

Nightjet sleeper: Vienna or Salzburg to Paris by Nightjet sleeper train: See passholder prices.
Passholder reservations for Nightjet sleeper trains can be made online at the ÖBB website using Method 1, see the instructions below.

Austria ► Germany

Intercity, EuroCity, ICE, railjet trains:
On EuroCity (EC), Intercity (IC), ICE & railjet trains from Austria to Germany, seat reservation is usually optional, if you like you can just hop on, sit in any empty unreserved seat & show your pass when asked. But reserving a seat is always a good idea for a long journey.
To reserve a seat, use the DB (German Railways) website as explained here or the ÖBB (Austrian Railways) website using Method 2 as explained here. It's just a normal seat reservation, the same as any fare-paying passenger would buy.
Which should you use, DB or ÖBB?
DB charge €5.20 2nd class or €6.50 1st class. ÖBB only charges €3 in either class, so ÖBB is cheaper.
However, DB lets you select your seat from a seat map on German IC and ICE trains, ÖBB only offers basic aisle, window, table options. On the other hand, ÖBB lets you select your seat from a seat map on Vienna-Salzburg-Munich railjets, while DB only offers basic aisle, window, table options. If choosing your seat is important to you, choose the right site for the right train!

BRB trains: Salzburg to Munich by BRB regional train
Seat reservation is neither necessary nor possible on these regional trains, just hop on and sit anywhere you like.

Westbahn: Vienna & Salzburg to Munich by Westbahn train
Interrail & Eurail passes give unlimited travel in Standard (2nd) class on Westbahn, seat reservation optional. If you have a 1st class pass, you can either sit in a Standard class seat for free or pay for an upgrade to sit in a Westbahn Comfort class or First class seat.
You can reserve a seat in Standard class for €4.90 or pay for a €9.90 upgrade to Comfort or €34.90 upgrade to First with reservation included.

Go to www.westbahn.at, change DE to EN top right for English and click Reservations.

Nightjet sleeper: Austria to Germany by Nightjet sleeper train
Vienna or Innsbruck to Koblenz, Cologne, Düsseldorf and Vienna to Berlin: See passholder prices.
Vienna or Innsbruck to Hannover or Hamburg by new generation Nightjet: See passholder prices here.
Passholder reservations can be made online at the ÖBB website using Method 1, see the instructions below.

Austria ► Netherlands

Nightjet sleeper: Vienna to Amsterdam by Nightjet sleeper train: See passholder prices.
Passholder reservations can be made online at the ÖBB website using Method 1, see the instructions below.

Austria ► Switzerland

Railjet or EuroCity: Vienna, Salzburg, Graz or Innsbruck to Zurich by railjet or EuroCity train
Seat reservation is optional on daytime trains between Austria & Switzerland, you can hop on any train, sit in any empty unreserved seat and show your pass when asked. However, reserving a seat is a good idea for a long journey, especially in summer or at other busy times. This is a lovely ride through the scenic Arlberg Pass, see the photos, tips & information on the Arlberg Railway page.
If you want to reserve a seat, you can make a reservation for around €3 at the Austrian Railways website using Method 2, see the instructions here.
Nightjet sleeper: Vienna to Zurich by Nightjet sleeper train: See passholder prices.
Passholder reservations can be made online at the ÖBB website using Method 1, see the instructions below.

Austria ► Italy

Railjet trains from Innsbruck to Verona, Bologna, Venice:
There is a passholder surcharge for travel on these Brenner Pass railjet trains, €10 in 2nd class or €15 in 1st class.

A reserved seat is optional, this costs an extra €3 per seat.

You can pay the surcharge and (if you want) make a seat reservation at the Austrian Railways website using Method 1, see the instructions below.
Or you can board the train without a reservation, sit in any empty unreserved seat and pay the surcharge plus an additional €5 on board the train.
Railjet trains Vienna to Venice: By railjet train from Vienna or Villach to Venice
There is a passholder surcharge for travel on these Vienna-Venice railjet trains, €10 in 2nd class or €15 in 1st class.
A reserved seat is optional, this costs an extra €3 per seat.

You can pay the surcharge and (if you want) make a seat reservation at the Austrian Railways website using Method 1, see the instructions below.
Or you can board the train without a reservation, sit in any empty unreserved seat and pay the surcharge plus an additional €5 on board the train.
EuroCity train Vienna to Trieste:
There is a passholder surcharge for travel on the extension into Italy, €2.60 in 2nd class, €4.60 in 1st class.
You can pay the surcharge and (if you like) make a seat reservation at the Austrian Railways website using Method 1, see the instructions below.
Nightjet sleeper: Vienna or Salzburg to Venice, Milan, Florence or Rome By Nightjet sleeper train: See passholder prices.
Passholder reservations for Nightjet sleeper trains can be made online at the ÖBB website using Method 1, see the instructions below.

Austria ► Hungary

Railjet or EuroCity: Vienna, Salzburg, Innsbruck to Budapest by railjet (RJ or RJX), EuroCity (EC) or other express train (D)
Reservation is optional, you can hop on any train and show your pass, nothing more to pay unless you want a reserved seat. However, reserving a seat is a good idea at busy times such as Friday or Sunday afternoons.
You can reserve a seat for around €3 at the Austrian Railways website using Method 2, see the instructions here.
Regiojet: Vienna to Budapest by private operator Regiojet, a few trains per day, www.regiojet.com)
Seat reservation required, €1.3 in Low Cost, €2 in Standard, €2.8 in Relax or (only if you have a 1st class pass) €1.3 in Business.
Regiojet passholder reservations can be made online at www.regiojet.com: Use the journey planner as if buying a normal ticket. When prices appear, look for the Only seat reservations toggle and use it. Select the train you want, then under Type of ticket purchased select Interrail & Eurail. You print out your reservation or can show it in the Regiojet app.
Alternatively, approach staff on the train before departure or go to the Regiojet/Student Agency sales point at Vienna Hbf. More about Vienna to Budapest trains.

Austria ► Czech Republic

Railjet: Vienna to Prague by ÖBB railjet train
Reservation is optional, you can hop on any train and show your pass, nothing more to pay unless you want a reserved seat. However, reserving a seat is a good idea in summer and at busy times such as Friday or Sunday afternoons.
You can reserve a seat for around €3 at the Austrian Railways website using Method 2, see the instructions here.
Regiojet: Vienna to Prague by Regiojet train
Seat reservation required, €1.3 in Low Cost, €2 in Standard, €2.8 in Relax or (only if you have a 1st class pass) €1.3 in Business.

Regiojet passholder reservations can be made online at www.regiojet.com: Use the journey planner as if buying a normal ticket. When prices appear, look for the Only seat reservations toggle and use it. Select the train you want, then under Type of ticket purchased select Interrail & Eurail. You print out your reservation or can show it in the Regiojet app.

Alternatively, you can approach staff on the train before departure or go to the Regiojet/Student Agency sales point at Vienna Hbf. More about Vienna to Prague Regiojet trains.
Vienna to Český Krumlov via Ceské Velenice:
This is all on regional trains, so no reservation necessary or possible, just hop on and show your pass. However, Interrail & Eurail passes don't cover the GWTR local trains between České Budějovice and Český Krumlov, this only costs €1.80 or so, you can pay on board the GWTR train using the ticket machines which take cash & contactless cards. How to plan this journey.

Austria ► Slovakia

Regional Express: Vienna to Bratislava by hourly regional express train
Hop on and sit in any empty seat, show your pass when asked. No reservation necessary or even possible.

Railjet: Vienna to Bratislava by once per day railjet
Reservation is optional, you can hop on the train and show your pass with nothing more to pay unless you want a reserved seat. Reserving a seat is a good idea at busy times such as Friday or Sunday afternoons.
You can reserve a seat for around €3 at the Austrian Railways website using Method 2, see the instructions here.
Intercity: Vienna to Košice & Slovakia by InterCity (IC)
Reservation is required, this varies from €3-€12 in 2nd class or €13-€22 in 1st class depending on distance.
You can reserve a seat at the Austrian Railways website using Method 2, see the instructions here.

Austria ► Poland

EuroCity: Vienna to Krakow or Warsaw by EuroCity train
Reservation is compulsory, seat reservation fee €3 in either class.
This is just a normal seat reservation like any other passenger with a pre-existing ticket would make, you can make a reservation online at the ÖBB website for €3 using Method 2, see the instructions here.
EuroNight sleeper train: Vienna to Krakow or Warsaw by EuroNight sleeper train
€29 for a couchette in 6-berth, €39 for a couchette in 4-berth, €44 for a bed in a 3-bed sleeper, €59 for a bed in a 2-bed sleeper, €119 for a bed in a single-bed sleeper, €79 for a bed in a 2-bed sleeper with shower & toilet, €139 for a bed in a single-bed sleeper with shower & toilet (all can be booked with a 2nd class pass).

Passholder reservations for this train can be made online at the Austrian Railways website using Method 1, see the instructions below, but only for this eastbound direction as a hard-copy reservation ticket must be collected in Austria.

Austria ► Slovenia, Croatia, Serbia

EuroCity: Vienna to Ljubljana or Zagreb by EuroCity train
Reservation is optional, you can hop on any train and show your pass, nothing more to pay unless you want a reserved seat. You can make a normal seat reservation for around €3 at the Austrian Railways website using Method 2, see the instructions here.

Austria ► Romania

Sleeper: Vienna to Sighisoara, Brasov or Bucharest by Dacia Express sleeper
Couchette in 6-berth €13.40, couchette in 4-berth €20, bed in 3-berth sleeper €28, bed in 2-berth sleeper €42. Bed in single-berth sleeper (requires 1st class pass) €98.

Passholder reservations for this train can be made online at the ÖBB website using Method 1, see the instructions below.

Belgium

What's covered?

Interrail & Eurail passes give unlimited travel on Belgian National Railways (SNCB), www.belgiantrain.be.

That includes all domestic local & mainline trains run by SNCB and (if you've a global pass) international trains to or from neighbouring countries run by SNCB & the partner railways in those countries.

Help with train times

For train times within Belgium see www.belgiantrain.be
See international train times & routes from Brussels
See international train times & routes from Bruges

Using a pass within Belgium

Using a railpass in Belgium is easy, as reservation is not necessary or even possible on Belgian domestic trains. You can simply hop on any train, find an empty seat and show your pass when asked.
There are two exceptions:

The Brussels airport trains require a €5.20 supplement, paid at the station or on board the train.

Eurostar (formerly Thalys) high-speed trains are reservation compulsory and carry a hefty €15+ passholder reservation fee, so avoid using them for domestic Belgian journeys such as Brussels-Antwerp or Brussels-Liege, use the alternative Belgian InterCity trains for free instead.

Belgium ► Great Britain

Eurostar: Brussels to London by Eurostar

Eurail & Interrail passes cover Eurostar from Brussels to London on payment of a special passholder fare of €35 in Standard or (if you have a 1st class pass) €40 in Plus.

You can make Eurostar passholder reservations online as explained here.

Belgium ► France

Eurostar (formerly Thalys): Brussels to Paris by Eurostar (formerly Thalys) high-speed train
Passholder reservation fee €27 in 2nd class, €32 in 1st class.

Passholder places are limited by quota which can sell out even if the train isn't full, so book ahead.

You can make Eurostar passholder reservations using either (1) Raileurope.com as explained here, (2) b-europe.com as explained here or (3) the official Eurail/Interrail reservations service. I recommend Raileurope as there's no booking fee and you are offered seating options.

Tip: There's an alternative to Eurostar to save money or if all Eurostar tickets have sold out: You can travel from Brussels to Paris using regional trains Brussels-Charleroi-Maubeuge-Paris as shown here as Brussels-Paris option 3. It takes around 4h30, there's only 1-3 departures per day with 2 changes of train, but no reservations are necessary, no extra to pay, just board the trains and show your pass.
TGV: Brussels to Lyon, Avignon, Marseille etc., by direct TGV by-passing Paris
A passholder reservation fee applies, €20 in 2nd class, €30 in 1st class.

Passholder tickets be booked online using either (1) Raileurope.com as explained here or (2) the Eurail/Interrail reservations service.
I recommend using Raileurope as there's no booking fee and it gives you seating options. It's e-ticketed, the reservation is emailed to you in minutes.
Ouigo: Unfortunately, Interrail & Eurail are not valid on the several slower Ouigo trains linking Brussels & Paris.
Regional trains: Brussels to Lille by regional train
No reservation is necessary or even possible for cross-border regional trains from Belgium to France.

Belgium ► Netherlands

Eurostar (formerly Thalys): Brussels to Rotterdam & Amsterdam by Eurostar (formerly Thalys) high-speed train

Passholder reservation fee €22 in 2nd class, €27 in 1st class.

Passholder places are limited by quota which can sell out even if the train isn't full, so book ahead.

You can make Eurostar passholder reservations at Raileurope.com as explained here, or b-europe.com as explained here or using the official Eurail/Interrail reservations service. I recommend Raileurope as there's no booking fee and you are offered seating options.

You can avoid the need for any reservation or fee by using the only slightly slower Eurocity Direct (ECD) or Eurocity (EC) trains.
Eurocity Direct (ECD) trains: Brussels-Antwerp-Rotterdam-Amsterdam Zuid by fast hourly Eurocity Direct train.

No reservation necessary or possible, just hop on, sit in any empty seat and show your pass when asked. Check times at www.b-europe.com.
Eurocity (EC) trains from Brussels-Antwerp-Breda-Rotterdam

No reservation necessary or possible, just hop on, sit in any empty seat and show your pass when asked. Check times at www.b-europe.com.
Incidentally, there is definitely no need to pay the Dutch €2.90 high-speed Intercity Direct supplement with an Interrail or Eurail pass.

Belgium ► Germany

ICE trains: Brussels to Cologne & Frankfurt by ICE high-speed train
Reservation is optional, you can just hop on, sit in any empty unreserved seat and show your pass when asked. However, a seat reservation is a good idea as these trains are often busy, you can make a normal seat reservation for around €5 at the German Railways website, see the instructions here.
Update: In summer from 1 June to 1 September, reservation is compulsory on these cross-border trains. If you find the German Railways website has had seat-only reservations disabled for this period, try using the Austrian Railways website (use Method 2, see the instructions here
Eurostar (formerly Thalys): Brussels to Cologne & Düsseldorf by Eurostar (formerly Thalys) high-speed train
Passholder reservation fee €27 in 2nd class, €32 in 1st class.

Passholder places are limited by quota which can sell out even if the train isn't full, so book ahead.

You can make Eurostar passholder reservations at Raileurope.com as explained here or b-europe.com as explained here or using the official Eurail/Interrail reservations service.
Tip: You can easily avoid fees by using the ICE trains between Brussels & Cologne instead.
European Sleeper: Brussels or Antwerp to Berlin by European Sleeper overnight train
Covered by Interrail & Eurail since July 2023. €16 for a seat, €47 for a couchette in 6-berth, €69 for a couchette in 5-berth, €99 for a bed in a 3-bed sleeper, €139 for a bed in a 2-bed sleeper or €169 for a bed in a single sleeper. Same price applies whether your pass is 1st or 2nd class.
You can make reservations at www.europeansleeper.eu by selecting Reservation Only instead of Adult in the Travel group box. booking.
Nightjet sleeper: Brussels to Berlin by Nightjet sleeper train: See passholder prices.
Passholder reservations for Nightjet sleeper trains can be made online at the ÖBB website using Method 1, see the instructions below.

Belgium ► Austria

Nightjet sleeper: Brussels to Vienna by Nightjet sleeper train: See passholder prices.
Passholder reservations for Nightjet sleeper trains can be made online at the ÖBB website using Method 1, see the instructions below.

Belgium ► Luxembourg

Intercity: Brussels to Luxembourg by hourly InterCity train
Seat reservation neither necessary nor possible, you can hop on any train and sit in any empty seat.

Belgium ► Czech Republic

European Sleeper: Brussels or Antwerp to Prague by European Sleeper overnight train
Covered by Interrail & Eurail since July 2023. €21 for a seat, €52 for a couchette in 6-berth, €74 for a couchette in 5-berth, €109 for a bed in a 3-bed sleeper, €149 for a bed in a 2-bed sleeper or €179 for a bed in a single sleeper. Same price applies whether your pass is 1st or 2nd class.
You can make reservations at www.europeansleeper.eu by selecting Reservation Only instead of Adult in the Travel group box. booking.

Bosnia

What's covered?

Interrail & Eurail passes give unlimited travel on all trains run by:
ZFBH (Railways of the Federation of Bosnia and Herzegovina) which operates the main line Doboj–Sarajevo–Mostar–Čapljina–Ploče.

ZRS (Railways of Republika Srpska) which covers Doboj–Banja Luka–Novi Grad–Dobrljin and Doboj–Petrovo Novo

At the time I write this, only a hard-copy (not mobile) Interrail or Eurail pass can be used on ZRS.

Reservation not required, even for the excellent ZFBH Talgo trains between Sarajevo & Mostar, Banja Luka and Bihac. Just board the train and sit in any empty seat, the conductor will accept your pass.

Help with train times

Bulgaria

What's covered?

Interrail & Eurail passes give unlimited travel on all trains run by Bulgarian State Railways (BDZ), www.bdz.bg.

That includes all domestic local & mainline trains run by BDZ and (if you've a global pass) international trains to or from neighbouring countries run by BDZ & the partner railways in those countries.

Help with train times

For train times within Bulgaria see www.bdz.bg
See international train times & routes from Sofia

Using a pass on national trains

Local trains, barz & patnicheski trains do not require reservations.
Seat reservation is compulsory on express trains (Expresen), this costs around €0.50 and can only be made at stations in Bulgaria.
Sleeper trains within Bulgaria: Bed in 3-bed sleeper €5.80, in 2-bed sleeper €7.80, in single-bed sleeper €15. Reservations can only be made at stations in Bulgaria.

Using a pass on international trains

Sofia to Bucharest or Sofia to Dimitrovgrad by daytime train:
Reservation is obligatory on international trains, but a seat reservation only costs around €1.50. Reservations cannot be made online, but there are always places available, just make reservations at the station. See tips for making reservations at Sofia station.
Sofia to Istanbul by sleeper train:
€10 supplement for a couchette in 4-berth compartment or €15 supplement for a bed in a 2-bed sleeper.

If you have a 1t class pass, a single-bed sleeper all to yourself costs €35.

You cannot make reservations online, you can make them at Sofia station international ticket windows or (as this train can leave fully-booked) or you can make reservations by emailing Andy on tickets@discoverbyrail.com, the same rail expert that runs www.discoverbyrail.com. Naturally, he charges a booking fee. Tickets are normally delivered to your hotel in Sofia or a personal handover can sometimes be arranged, ask for details.

Croatia

What's covered?

Interrail & Eurail passes give unlimited travel on all trains run by Croatian Railways (HZ), www.hzpp.hr.

That includes all domestic local & mainline trains run by HZ and (if you've a global pass) international trains to or from neighbouring countries run by HZ & the partner railways in those countries.
Passes are not accepted on Regiojet's summer-only sleeper train between Prague & Rijeka.

Help with train times

For train times within Croatia, see www.hzpp.hr

See international train times & routes from Zagreb

See international train times & routes from Dubrovnik & Split

Using a pass within Croatia

ICN trains between Zagreb & Split, Intercity trains between Zagreb & Rijeka, Osijek, Cakovec:

Seat reservation required, email Croatian Railways at rezervacije@hzpp.hr or make them at the station.
Zagreb-Split by sleeper train:

Couchette in 6-berth €7. Bed in 3-bed sleeper €9, bed in 2-bed sleeper €13, bed in single-bed sleeper €25.

Reservations cannot be made online, either make a reservation at the station or email rezervacije@hzpp.hr.

Using a pass on international trains

Zagreb to Ljubljana or Lesce-Bled:

Reservation optional, try asking for a reservation by email to rezervacije@hzpp.hr. Feedback appreciated, let me know if that email changes. You can also to reserve a seat for €3 at least on some departures, using the Austrian ÖBB website, see the instructions below. In this case, it's just an ordinary seat reservation, so you use the Seat reservation only - no ticket link to run the enquiry.
Zagreb to Vienna:

Seat reservation is optional, you can just get on the train, sit in any empty unreserved seat & show your pass when asked. If you want a reserved seat, this costs €3.

You can reserve a seat on from Zagreb to Vienna at the Austrian Railways website using Method 2, see the instructions below.

Zagreb to Budapest:

Seat reservation is compulsory, €3 per seat. It's just a normal seat reservation which can be made using using the Austrian Railways website (use Method 2, see the instructions here or at the CD (Czech Railways) website, see the instructions here.

Zagreb to Belgrade:

Seat reservation is optional, you can just get on the train, sit in any empty unreserved seat & show your pass when asked. If you want a reserved seat, this costs around €3.

You can reserve a seat on from Zagreb to Vienna at the Austrian Railways website using Method 2, see the instructions below.
Zagreb to Munich, Stuttgart or Zurich by sleeper train:

Couchette in 6-berth €29.90, couchette in 4-berth €34.90, bed in 3-bed sleeper €64.90, in 2-bed €109.90, in single-bed €234.90.

Prices vary slightly according to demand. All types of couchette or sleeper can be booked with any class of pass.

Passholder reservations for sleepers or couchettes can be made online at the ÖBB website using Method 1, see the instructions below.

Czech Republic

What's covered?

Interrail & Eurail passes give unlimited travel on Czech Railways (CD), www.cd.cz. That includes all domestic local & mainline trains run by CD and (if you've a global pass) international trains to or from neighbouring countries run by CD & the partner railways in those countries.
Passes also give unlimited travel on most Regiojet trains, see www.regiojet.com. However, passes are not accepted on Regiojet's summer-only sleeper train between Prague & Split/Rijeka.
Passes now also give unlimited travel on Leo Express trains, www.leoexpress.com.

What's not covered

Passes are not valid on private local train operators Arriva or GWTR.
Trains to Český Krumlov: Your pass covers the once daily direct train between Prague & Český Krumlov run by CD (Czech Railways). It also covers the regular trains run by CD between Prague or Linz & České Budějovice, which is the junction station for the local trains to Český Krumlov. But Interrail & Eurail passes don't cover the local trains from České Budějovice to Český Krumlov which are now operated by private operator GWTR. The fare is less than €2, so all you have to do is buy a ticket for this short 40-minute hop, either at the green & orange GWTR ticket kiosk at České Budějovice or using the machines on board the train which take contactless cards.

Help with train times

For train times within the Czech Republic see www.cd.cz.

See international train times & routes from Prague

See international train times & routes from Český Krumlov

Using a pass within the Czech Republic

SuperCity trains: Prague - Ostrava by SuperCity (SC) train.

Reservation compulsory for an €8 fee, you can make these reservations online at the CD website, see the instructions below.
EuroCity, InterCity & other express trains run by CD and its partner railways:

Reservation is optional. You can just board the train, sit in any empty seat and show your pass when asked. If you want a reserved seat this costs around €3, simply make a normal seat reservation using the CD (Czech Railways) website, see the instructions here.
Regiojet trains, for example Prague-Ostrava or Prague-Brno:

Seat reservation is compulsory, €1.3 in Low Cost, €2 in Standard, €2.8 in Relax or (if you have a 1st class pass) €1.3 in Business.

Regiojet passholder reservations can be made online at www.regiojet.com: Use the journey planner as if buying a normal ticket. When prices appear, look for the Only seat reservations toggle and use it. Select the train you want, then under Type of ticket purchased select Interrail & Eurail. You print out your reservation or can show it in the Regiojet app.

Alternatively, approach staff on the train before departure or go to the Regiojet/Student Agency sales point at Prague Hlavni.
Leo Express trains:

2nd class passes are valid in economy, 1st class passes in business class (or standard plus class), reservation is required but free of charge.

You can make passholder reservations in person at their Prague or Ostrava offices or online at leoexpress.com following the advice here. Upgrade to Premium class is not possible.

Czech Republic ► Belgium

European Sleeper: Prague to Antwerp or Brussels by European Sleeper overnight train
Covered by Interrail & Eurail since July 2023. €21 for a seat, €52 for a couchette in 6-berth, €74 for a couchette in 5-berth, €109 for a bed in a 3-bed sleeper, €149 for a bed in a 2-bed sleeper or €179 for a bed in a single sleeper. Same price applies whether your pass is 1st or 2nd class.
You can make reservations at www.europeansleeper.eu by selecting Reservation Only instead of Adult in the Travel group box. booking.

Czech Republic ► Netherlands

European Sleeper: Prague to Amsterdam or Rotterdam by European Sleeper overnight train
Covered by Interrail & Eurail since July 2023. €16 for a seat, €47 for a couchette in 6-berth, €69 for a couchette in 5-berth, €99 for a bed in a 3-bed sleeper, €139 for a bed in a 2-bed sleeper or €169 for a bed in a single sleeper. Same price applies whether your pass is 1st or 2nd class.
You can make reservations at www.europeansleeper.eu by selecting Reservation Only instead of Adult in the Travel group box. booking.

Czech Republic ► Germany

EuroCity trains to Dresden & Berlin
Reservation is optional on Prague-Berlin EuroCity trains, if you like you can just hop on, sit in any empty unreserved seat & show your pass when asked. However, it gets busy in summer and on Fridays & Sundays all year so I strongly recommend reserving a seat.
Update: In summer from 1 June to 1 September, reservation is compulsory on these cross-border trains.
You can make a seat reservation using either the DB (German Railways) site as explained here or the CD (Czech Railways) site as explained here.
DB charge €5.20 in 2nd class, €6.50 in 1st class. CD charge €3 in either class.
Tip: Not only is CD cheaper, they usually let you choose your seat from a seat map, DB doesn't. So it's a no-brainer to use CD!
EuroCity trains to Munich: Prague to Munich by EuroCity train
Reservation is optional, you can just board the train, sit in any empty seat and show your pass when asked. See photos, tips & information for Prague to Munich trains.
If you want a reserved seat, simply make a normal seat reservation at the CD (Czech Railways) website, see the instructions here.
Prague to Nuremberg & Frankfurt via Cheb or Schwandorf:
You can check times from Prague to Germany via these two useful routes at www.cd.cz, clicking Advanced options, then Travel via and then entering Cheb or Schwandorf in the via box. Reservation is unnecessary on these routes route (unless the Prague-Cheb train is a SuperCity (SC) trains when a €7 fee applies, you can make a Prague-Cheb SuperCity reservation at the CD website, see the instructions here).

Czech Republic ► Austria

Railjet trains: Prague to Vienna by ÖBB/CD railjet train
Reservation is optional, you can just board the train, sit in any empty seat and show your pass when asked. However, reserving a seat for around €4 is a good idea on this busy route, especially in summer or on Friday & Sunday afternoons at any time of year. See photos, tips & information for Prague to Vienna trains.

If you want a reserved seat, simply make a normal seat reservation at the CD (Czech Railways) website, see the instructions here.
Regiojet: Prague to Vienna by Regiojet
Seat reservation required, €1.3 in Low Cost, €2 in Standard, €2.8 in Relax or (only if you have a 1st class pass) €1.3 in Business.

Regiojet passholder reservations can be made online at www.regiojet.com: Use the journey planner as if buying a normal ticket. When prices appear, look for the Only seat reservations toggle and use it. Select the train you want, then under Type of ticket purchased select Interrail & Eurail. You print out your reservation or can show it in the Regiojet app.

Alternatively, approach staff on the train before departure or go to the Regiojet/Student Agency sales point at Prague Hlavni. See the photos, video, tips & info on the Prague to Vienna page.
EuroCity trains to Linz: Prague to Linz by EuroCity train, for Salzburg & Innsbruck
Reservation is optional on both the Czech train from Prague to Linz and the onward Austrian railjet trains to Salzburg & Innsbruck. You can just board the train, sit in any empty seat and show your pass when asked. See the photos, video, tips & info on the Prague to Salzburg page.
If you want a reserved seat, you can make a seat reservation at the CD (Czech Railways) website, see the instructions here. You can make a seat reservation from Linz to Salzburg or Innsbruck at the Austrian Railways website using Method 2, see the instructions here.

Czech Republic ► Switzerland

EuroNight sleeper: Prague to Zurich by EuroNight sleeper train (both routes)
With a 2nd class pass, bed in 3-berth sleeper €45, bed in 2-berth sleeper €58, bed in single-berth sleeper €110. With a 1st class pass, bed in 3-berth deluxe sleeper with shower & toilet €45, bed in 2-berth deluxe sleeper with shower & toilet €58, bed in single-bed deluxe sleeper with shower & toilet €110.

Passholder reservations for Prague to Zurich sleeper trains can be made online at the Czech Railways website www.cd.cz. Before running the enquiry, click where it says 1 x Adult 26-64 No discount card then click on No discount card , click Interrail and Eurail Pass then select the one you have. You print your own ticket or can show it on your phone.
Daytime trains: Prague to Zurich by daytime trains with a change at Munich or Linz/Salzburg
None of the daytime trains Prague-Munich & Munich-Zurich or Prague-Linz and Linz-Salzburg-Zurich require reservations, you can just hop on and show your pass when asked. Seat reservations are optional, you can make a normal seat reservation from Prague to Munich or Linz at the CD (Czech Railways) website as shown here. You can make a normal seat reservation from Munich to Zurich at the German Railways website as shown here or from Linz or Salzburg to Zurich at the Austrian Railways website using Method 2, see the instructions here.

Czech Republic ► Hungary

EuroCity trains: Prague to Budapest by EuroCity train
Reservation is optional, so you can just board the train, sit in any empty seat and show your pass when asked. However, reserving a seat for around €3 is a good idea. More about Prague to Budapest EuroCity trains.

If you want a reserved seat, simply make a normal seat reservation at the CD (Czech Railways) website, see the instructions here.
Sleeper train: Prague to Budapest by sleeper train
€21 for a bed in a 3-berth sleeper, €31 for a bed in a 2-bed sleeper, €72 in a single-bed sleeper, all bookable with a 2nd class pass. More about the Prague to Budapest sleeper train.
Passholder reservations for Budapest to Prague sleeper berths can be made online at the Czech Railways website www.cd.cz, with no added booking fee. Before running the enquiry, click where it says 1 x Adult 26-64 No discount card then click on No discount card , click Interrail and Eurail Pass then select the one you have. You print your own ticket or can show it on your phone.
Regiojet: Prague to Budapest by private operator Regiojet
Seat reservation required, €1.3 in Low Cost, €2 in Standard, €2.8 in Relax or (only if you have a 1st class pass) €1.3 in Business.

Regiojet passholder reservations can be made at www.regiojet.com: Use the journey planner as if buying a normal ticket. When prices appear, look for the Only seat reservations toggle and use it. Select the train you want, then under Type of ticket purchased select Interrail & Eurail. You print out your reservation or can show it in the Regiojet app.

Alternatively, approach staff on the train before departure or go to the Regiojet/Student Agency sales point at Prague Hlavni.

Czech Republic ► Slovakia

EuroCity train: Prague to Bratislava by EuroCity train
Reservation optional, so nothing to pay unless you want a reserved seat for €4. If you want a reserved seat, you can make a normal seat reservation at the CD (Czech Railways) website, see the instructions here.
SuperCity train: Prague to Poprad Tatry & Košice by fast tilting SuperCity (SC) trains
Reservation compulsory, €8 reservation fee. Simply make a normal seat reservation at the CD (Czech Railways) website, see the instructions here.
Regiojet: Prague to Bratislava, Poprad Tatry, Košice & Slovakia by Regiojet train
Seat reservation required, €1.3 in Low Cost, €2 in Standard, €2.8 in Relax or (only if you have a 1st class pass) €1.3 in Business.
Regiojet passholder reservations can be made online at www.regiojet.com: Use the journey planner as if buying a normal ticket. When prices appear, look for the Only seat reservations toggle and use it. Select the train you want, then under Type of ticket purchased select Interrail & Eurail. You print out your reservation or can show it in the Regiojet app.
Alternatively, approach staff on the train before departure or go to the Regiojet/Student Agency sales point at Prague Hlavni.

Czech Republic ► Poland

EuroCity train: Prague to Krakow or Warsaw by EuroCity train
Reservation is compulsory, but you only need a normal seat reservation for around €3.50.
You can reserve a seat online at the CD (Czech Railways) website, see the instructions here.

EuroNight Sleeper train: Prague to Krakow or Warsaw by EuroNight sleeper train
€13.40 per person in 6-bunk couchette, €?? in 4-bunk couchette, bed in 3-bed sleeper €20, bed in 2-bed sleeper €30, bed in single-bed sleeper €70, bed in 2-bed sleeper with shower & toilet €??, bed in single-bed sleeper with shower & toilet €80.

Passholder reservations for the Prague to Krakow/Warsaw sleeper train can be made online at the Czech Railways website www.cd.cz. Before running the enquiry, click where it says 1 x Adult 26-64 No discount card then click on No discount card , click Interrail and Eurail Pass then select the one you have. You print your own ticket or can show it on your phone.

Leo Express: Prague to Krakow by Leo Express (see timetable here)
2nd class passes entitle you to free travel in economy, 1st class passes to free travel in standard plus or business class. Reservation is required but free of charge, you can make passholder reservations in person at their Prague or Ostrava offices or online at leoexpress.com following the advice here. Upgrade to Premium class is not possible.

Denmark

What's covered?

Eurail & Interrail passes give unlimited travel on all trains run by DSB = Danish State Railways, www.dsb.dk.

That includes all domestic local & mainline trains run by DSB and (if you've a global pass) international trains to or from neighbouring countries run by DSB & its partner railways in those countries such as SJ (Sweden), DB (Germany).

Passes also cover local trains run by GoCollective (formerly Arriva).
Passes give free travel on the Öresund trains between Copenhagen, Malmö & Gothenburg.

Other pass benefits

30% discount on Stena Line ferries (including Frederikshavn-Gothenburg)

Help with train times

For train times within Denmark www.dsb.dk.

See international train times & routes from Copenhagen

Using a pass within Denmark

No reservations necessary and nothing extra to pay on any normal Danish domestic train, including Danish InterCity trains. Just hop on and show your pass. Optional reserved seat on longer-distance trains €3.90 per seat.

Denmark ► Germany

Intercity trains: Copenhagen to Hamburg by InterCity train

Reservation is usually optional, but strongly recommended as these trains get very busy.
Update: In summer from 1 June to 1 September, reservation is compulsory on these cross-border trains.
You can make a seat reservation for €5.20 in 2nd class or €6.50 in 1st class using the DB (German Railways) website as explained here. If your journey involves more than one train from Denmark to your German destination, you only pay one reservation fee for the whole journey.
Or for €4 per seat/train at the Danish Railways website, see the instructions here.
Or for €3 per seat/train at the Austrian Railways website using Method 2, see the instructions below.

Denmark ► Sweden

Öresund train: Copenhagen to Malmö & Gothenburg by Öresund train
No reservation necessary, you can just hop on any train, sit where you like and show your pass when asked.
X2000: Copenhagen to Stockholm by X2000 train
Reservation compulsory, passholder reservation €6.60 in 2nd class, €16 in 1st class.
You can make passholder reservations at www.sj.se following the instructions below with no added booking fee. The reservation is e-ticketed and emailed to you.
You can also make them using the Eurail/Interrail reservations service, also e-ticketed and emailed to you.
You can also make them at www.trainplanet.com, remembering to first switch it to Interrail mode using the toggle under the journey planner. Trainplanet adds a small booking fee.

Snälltåget run Copenhagen to Stockholm once or twice a day through the summer, in competition with SJ:
Reservation required, €5 in 2nd class, €15 in 1st class.
You can make a passholder reservation online at www.snalltaget.se/en, simply tick the I have an Interrail or Eurail Pass box in the Travellers panel.

Estonia

What's covered?

Eurail & Interrail passes give unlimited travel on all trains run by Estonian railways = Elron, elron.ee.

Other pass benefits

Special fares on Tallink-Silja Line ferries Helsinki-Tallinn, Stockholm-Tallinn.

Help with train times

For trains within Estonia, see elron.ee.

See international train times & routes from Tallinn.

Using a pass on national trains

Fares are very cheap in Estonia so don't buy a pass for Estonia before checking normal train fares.
Reservations aren't necessary and aren't even possible in 2nd class, just hop on and show your pass.
Seat reservation is required in 1st class, reservations can only be made at Estonian stations, not online.

Finland

What's covered?

Eurail & Interrail passes give unlimited travel on all trains run by VR = Finnish state railways, www.vr.fi.

Other pass benefits

50% discount on Viking Line ferries Stockholm-Helsinki and Stockholm-Turku.
Special fares on Tallink-Silja Line ferries Stockholm-Helsinki, Stockholm-Turku, Helsinki-Tallinn.
30% discount on Finnlines ferries Helsinki-Travemünde & Helsinki-Rostock (Germany).

Help with train times

For trains within Finland, see www.vr.fi.

See international train times & routes from Helsinki.

Using a pass within Finland

Reservation on InterCity & Pendolino trains is optional, if you want a reserved seat it costs 25% of a full-price ticket.
Sleeper trains to northern Finland: You pay 50% of the full-price for a compartment. Only whole compartments are bookable.
You can make passholder reservations at the station or by phone to VR at +358 923 192 902, you can check this number at www.vr.fi.

France

What's covered and not covered

Using a pass on trains within France

How to make reservations within France

How to make reservations from France to Britain, Belgium, Netherlands, Luxembourg, Switzerland, Italy, Spain, Germany, Austria

What's covered?

Eurail & Interrail passes give unlimited travel on all trains run by SNCF = French national railways, www.sncf-connect.com/en.

That includes all domestic local & mainline trains run by SNCF and (if you've a global pass) international trains to/from neighbouring countries run by SNCF & partner railways including Eurostar to London, Eurostar (formerly Thalys) to Brussels, Amsterdam & Cologne, TGV-Lyria to Switzerland, TGV to Barcelona, TGV to Turin or Milan, and TGV/ICE trains to Germany. The Mont-Blanc Express is covered, as it's run by SNCF.
Virtually all major international trains to or from France require reservation, as explained below

What's not covered?

Passes don't cover Paris metro or RER (express metro) routes run by transit authority RATP, but are valid on a few RER routes run by SNCF.
Passes don't cover Ouigo lo-cost trains. Ouigo is a separate company, even though it's an SNCF subsidiary.
Passes don't cover Trenitalia's Frecciarossas on the Paris-Lyon-Turin/Milan route as Trenitalia France is a separate company (but they cover SNCF TGVs on this route).
Passes don't cover the Nice-Digne private railway.

Other pass benefits

30% discount on Irish Ferries (www.irishferries.com) direct France-Dublin ferries. You cannot book online with this discount, but call them and it can be done over the phone or at the port.

Help with train times

For trains within France see www.raileurope.com.

See international train times & routes from Paris

See international train times & routes from Nice

See international train times & routes from Marseille

See international train times & routes from Lyon

See international train times & routes from Bordeaux

See international train times & routes from Toulouse

See international train times & routes from Montpellier

See international train times & routes from Strasbourg

Using a pass in France

In France, you must pay a passholder reservation fee for almost all long-distance trains.
TGV high-speed trains
TGVs run on major long distance routes, seat reservation compulsory for either €10 or €20.

There are a limited number of €10 passholder places on each TGV, when these sell out a €20 fee applies until the train is full.

On some trains, 2nd class passholders are offered an optional upgrade to 1st class for €30-€58, but only if you book using option 2 below.

Passes are not valid on lo-cost Ouigo TGVs as Ouigo is a separate company, even though an SNCF subsidiary.

Intercités
On Intercités with compulsory reservation, the reservation fee is either €10 or €20.
Routes include Paris-Limoges-Brive-Toulouse, Paris-Vichy-Clermont Ferrand, Bordeaux-Toulouse-Marseille-Nice. A limited number of €10 passholder reservations is offered on each TGV, when these sell out the €20 fee applies until the train is full.
On Intercités without compulsory reservation, an optional seat reservation costs €1.60.
Such routes include Nantes-Bordeaux, Béziers-Clermont Ferrand, Nantes-Lyon & Toulouse-Hendaye. If you don't to reserve a seat you can simply get on and sit in any unreserved seat.

Intercités de nuit sleeper trains

Intercités de nuit overnight trains run on routes such as Paris-Nice, Paris-Toulouse-Latour de Carol, Paris-Lourdes:

Reclining seat €10, couchette in 2nd class 6-bunk compartment €21.60 or in 1st class 4-berth compartment (with 1st class pass) €21.60.

Tip: You can book a whole compartment for sole occupancy by 1-6 people if you buy normal point-to-point tickets (see the espace privatif information here) but this is not possible when you are using an Interrail or Eurail pass.

Trains Nomad, Paris-Normandy
Trains Nomad is the brand name for trains between Paris & Normandy, including Paris-Caen-Cherbourg, Paris-Rouen-Le Havre. Seat reservation is compulsory when travelling to or from Paris, €1.70. However, reservation is not necessary for journeys that don't involve Paris.
Confusingly, as they're operated by the Normandy region they are shown as TER in some ticketing systems/timetables. You can make Train Nomad reservations using Raileurope.com as explained here or using SNCF ticket machines at stations as described below.
TER regional trains
Reservation is not necessary or even possible on most Trains Express Régionaux (TER). Just hop on, sit in any empty seat and show your pass when asked.
However, from 6 July 2024 there will be a few exceptions: The TER-Est express services from Paris to Troyes & Mulhouse, and Paris to Châlons en Champagne & Strasbourg will become reservation compulsory, fee for passholders €1.70. Hopefully reservations will be possible using Raileurope.com as explained here, and using SNCF ticket machines at stations as described below.

How to make reservations for France

You cannot make passholder reservations at the French Railways website sncf-connect.com. You must use one of these websites instead:
Option 1, using Raileurope.com as explained here.

Raileurope are top choice for making passholder reservations for France because (1) at the time I write this they charge no added booking fee, just the cost of the reservation, (2) you can check availability before buying a pass (is it €10 or €20 on your train?) and (3) it lets you choose window, aisle, upper or lower deck on a TGV Duplex.

Raileurope can reserve seats on TGVs & Intercités, also seats & couchettes on Intercités de nuit, also Trains Nomad. It can also do passholder reservations for most international trains to/from France, but not Nightjet sleepers or AVE trains run by Renfe.

Booking usually opens 4 months ahead. It's e-ticketed, the reservation is emailed to you within minutes.
Option 2, using the Eurail/Interrail reservations service.

This system can reserve TGVs, Intercités & Intercités de nuit, but not Trains Nomad. Seats are assigned, there is no seating choice and your seat numbers are only revealed after you confirm and pay. There's a small booking fee. You may find that reservations only open 90 days ahead. It's e-ticketed, the reservation is emailed to you within minutes.
Option 3, using travel.b-europe.com/Eurail-GE/en/booking-tgv.

This website lets you check availability and prices before you buy a pass, you only need a pass number to make the reservation.

On some trains, 2nd class passholders may be offered an optional upgrade to 1st class when using this website, a key advantage!

As you can see from the URL, this is a page run by the Belgian Railways, but it's re-badged for the Interrail/Eurail organisation and not accessible via the normal B-europe.com home page. This special page is designed to be accessed via the Interrail/Eurail Railplanner app for in-app reservations, but there's no reason why you can't use it directly on a desktop or laptop if you know the URL to access it (which you do, I just gave it to you!). Bookings open up to 4 months ahead. They charge a small booking fee.

If it won't accept your mobile pass number, generate a pass cover number from your mobile pass number using this special page: www.eurail.com/en/book-reservations#/generatePassCoverNumber.
Option 4, call SNCF telesales

You can make passholder reservations on French trains by calling SNCF telesales on 00 33 184943635, option 85. Lines open 08:00-20:00 French times, 7 days a week.
Option 5, at stations using SNCF ticket machines - easy!

You can make passholder reservations at SNCF's staffed counters, but it's quicker to use one of the many SNCF ticket machines. The ability to make passholder reservations was removed from these machines for a while, but from 2024 it's back, and easy to use.

Click the UK flag at the bottom of the screen for English.

Click Buy a ticket and set up an enquiry as if buying a ticket. See screenshot.

After entering the number of passengers there's a screen that says Do you have a reduction or pass? See screenshot.

Eurail & Interrail aren't listed on that first page, so click OTHER REDUCTIONS and EURAILPASS & INTERRAIL appear, select one. See screenshot.

Then run the enquiry and choose a train.

You will see two prices, Alterable with conditions and Alterable. The cheaper one is the pass reservation that you expect to see, €10 or €20 for a TGV, the other prices (which could be over €100) is a normal ticket. Just keep your wits about you! See screenshot.

Incidentally, you should normally only make a 1st class reservation if you have a 1st class pass. But on TGV & Intercités you may get an upgrade price (perhaps €58 or so) if you say you have a 2nd class pass but ask for a 1st class reservation. Just keep your wits about you to avoid accidentally buying a normal ticket at the full non-pass price!

France ► Great Britain

Eurostar: Paris, Lille or Calais to London by Eurostar.
Eurail & Interrail passes cover Eurostar to London on payment of a passholder reservation fare of €35 in Standard if you have a 2nd class pass or €40 in Plus if you have a 1st class pass.
You can make Eurostar passholder reservations online as explained here.

France ► Belgium

Eurostar (formerly Thalys):
Paris to Brussels or Antwerp by Eurostar (formerly Thalys) high-speed train:
Reservation compulsory, €27 in 2nd class, €32 in 1st class.

Passholder places are limited by quota which can sell out even if the train isn't full - so book sooner rather than later!

You can make Eurostar passholder reservations at Raileurope.com as explained here or b-europe.com as explained here or using the official Eurail/Interrail reservations service.
TGV: Direct TGVs from Marseille, Avignon, Lyon & other French cities to Brussels:
Reservation compulsory, €20 in 2nd class, €30 in 1st class.

Passholder tickets be booked online using either (1) Raileurope.com as explained here or (2) the Eurail/Interrail reservations service.
I recommend using Raileurope as you can select seating options. It's e-ticketed, the reservation is emailed to you within minutes.
Ouigo: Unfortunately, Interrail & Eurail are not valid on the several slower Ouigo trains linking Brussels & Paris.

Regional trains: Lille to Brussels by regional train
No reservation is necessary or even possible for cross-border regional trains from France to Belgium or for Intercity (IC or ICD) trains between Brussels & the Netherlands. Incidentally, Paris to Lille by TGV is either €10 or €20, see the France section.

France ► Netherlands

Eurostar (formerly Thalys):
Paris to Rotterdam or Amsterdam by Eurostar (formerly Thalys) high-speed train:
Reservation compulsory, €32 in 2nd class, €37 in 1st class.

Passholder places are limited by quota which can sell out even if the train isn't full - so book sooner rather than later!

You can make Eurostar passholder reservations at Raileurope.com as explained here or b-europe.com as explained here or using the official Eurail/Interrail reservations service.

France ► Luxembourg

TGV: Paris to Luxembourg by TGV:
Reservation compulsory, €10 fee in both classes.

You can make passholder reservations online at Raileurope.com as explained here or using the Eurail/Interrail reservations service. It's e-ticketed, the reservation is emailed to you within minutes.

France ► Switzerland

TGV-Lyria: Paris to Geneva, Lausanne, Basel or Zurich by TGV-Lyria TGV high-speed train:
Reservation is compulsory, €29 in 2nd class, €39 in 1st class. These new rates apply from 1 July 2023.

The good news is that TGV-Lyria passholder places shouldn't run out as they're taken from the most expensive price bucket.

You can make passholder reservations for TGV-Lyria at Raileurope.com as explained here or using the Eurail/Interrail reservations service. It's e-ticketed, the reservation is emailed to you within minutes.

If you can book 2-3 months ahead, regular advance-purchase tickets start at €29 including reservation, at www.thetrainline.com.
How to avoid paying the TGV-Lyria passholder fee:

Option 1, take a TER regional train from Paris to Mulhouse then a TER regional train from Mulhouse to Basel SBB, no reservation necessary or possible on either train. Find times using int.bahn.de: Click Mode of transport, select Local transport only then run a Paris-Basel enquiry.

Option 2, take a TGV from Paris to Strasbourg (€10 or €20 fee) then a TER regional train from Strasbourg to Basel. Find times using int.bahn.de, click Stopovers and enter Strasbourg, then run a Paris-Basel enquiry. Make the Paris-Strasbourg TGV reservation using the Eurail/Interrail reservations service.

Option 3, take one of the several Paris-Lyon TER regional trains (no reservation needed, just hop on & show your pass, but they take 5h rather than 2h by TGV) then another TER regional train from Lyon to Geneva (no reservation required, just hop on & show your pass). Find times using int.bahn.de: Click Stopover and enter Lyon Part Dieu, click Mode of transport and select Local transport only, then run a Paris-Geneva enquiry.

TER regional trains: Strasbourg to Basel by TER, Lyon to Geneva by TER, Mulhouse to Basel by TER: No reservation necessary or possible. just get on, sit anywhere you like and show your pass when asked.

France ► Italy

Paris to Turin or Milan by SNCF (French Railways) TGV train:
Reservation is compulsory, €31 in 2nd class, €45 in 1st class.
You can make passholder reservations at Raileurope.com as explained here or using the Eurail/Interrail reservations service. It's e-ticketed, the reservation is emailed to you.
Passholder places are controlled by quota, passholder places can run out even when there are plenty of seats left.
If booking well in advance, it may be cheaper to buy a normal ticket from just €29 2nd class, €46 in 1st class including reservation at www.raileurope.com or www.thetrainline.com - even if you already have a pass.
Can you avoid these fees between Paris & Italy? Not easily, as there are no local trains across the border on the direct Paris-Milan route. But you could consider going Paris-Nice by TGV (€10 fee, or €20 when the €10 reservations sell out) then using local trains along the Mediterranean coast from Nice to Ventimiglia then onwards into Italy. Find times from Nice to Italy using int.bahn.de, if you want to stick with fee-free regional trains click Mode of transport and select Local transport only. Look for trains marked TER, R & RV.
Paris or Lyon to Turin or Milan by Trenitalia (Italian Railways) Frecciarossa:

Passes aren't currently valid on Trenitalia's Paris-Lyon-Turin-Milan Frecciarossas, because when in France it is run by Trenitalia France which is not a signatory to the Interrail & Eurail schemes, even though it's a subsidiary of Trenitalia. But advance-purchase fares for the Frecciarossa start at €29 which is cheaper than the TGV passholder fee, so check normal prices using www.italiarail.com, www.raileurope.com or www.thetrainline.com.
Cannes, Nice, Monaco to Ventimiglia, San Remo, Savona, Genoa, Milan & Italy:
Travelling from the south of France to Italy means taking a TER regional train from Cannes, Nice or Monaco to Ventimiglia on the Italian border. No reservation is needed for this French TER train, just hop on any train and show your pass when asked.
If you travel onwards from Ventimiglia to San Remo, Savona, Genoa by slower Italian regional train, no reservation is needed for this French TER train, just hop on any train and show your pass when asked.
If you travel onwards from Ventimiglia to Savona, Genoa & Milan by faster Intercity train, a seat reservation is required, for prices and how to make a reservation on trains within Italy, see the Italy national trains section below.
For more information about this route, see the Nice to Italy by train page.

France ► Spain

French TGV trains, Paris & southern France to Barcelona:
Paris, Valence, Nimes, Montpellier, Perpignan, Narbonne to Girona, Figueres Barcelona by SNCF (French Railways TGV:
Reservation compulsory, a hefty €35 in 1st or 2nd class.

The same fee applies for shorter journeys on these trains, for example Perpignan-Barcelona. Passholder places are controlled by a quota, so can sell out even if the train isn't full.

Make passholder reservations online at Raileurope.com as explained here or using the Eurail/Interrail reservations service.
It's e-ticketed, the reservation is emailed to you and can be printed or shown on your phone.
Spanish AVE trains, Lyon & Marseille to Barcelona & Madrid: No longer a problem!

Every morning, an AVE S100 links Marseille, Avignon, Nimes, Montpellier, Perpignan, Narbonne to Barcelona & Madrid.

Every afternoon, an AVE S100 links Lyon, Nimes, Montpellier, Perpignan, Narbonne to Barcelona.

Operated by Renfe (Spanish Railways), they enter France on an open-access basis in competition with SNCF (French Railways).

The reservation fee is €10 in 2nd class, €13 in 1st class. A lot cheaper than SNCF's TGVs!
You can make passholder reservations on these trains using Raileurope.com as explained here, with no added booking fee.

Or you can use the Eurail/Interrail reservations service or use www.happyrail.com, a reliable Dutch agency, with a 3.5% booking fee (change Tickets to Reservations).

An e-ticket is emailed to you.

How to avoid the expensive Paris-Barcelona TGV reservation fee:
Option 1, Toulouse to Latour de Carol to Barcelona: There are no fees to pay or reservations required on the TER regional trains from Toulouse to Latour de Carol or on the Spanish Cercanias train from Latour de Carol through the Pyrenees to Barcelona, see here for details. Just turn up, hop on and show your pass when asked.
Option 2, Perpignan - Cerbère- Barcelona: Take a TGV from Paris to Perpignan, €10 reservation fee booked in advance or €20 fee when the €10 fees sell out, book this online using the Eurail/Interrail reservations service. Or travel to Perpignan from Montpelier, Avignon, Marseille, Nice or wherever. Then take a local TER regional train from Perpignan to either Cerbère or Portbou and a Spanish Rodalies local train along the scenic coast from Cerbère or Portbou to Barcelona Sants, no reservation necessary for either train. The easiest way to find Perpignan-Barcelona TER/Rodalies times is to use int.bahn.de: Click Stopovers and enter Portbou length of stay left as zero, click Mode of transport and select Local transport only, then run an enquiry from Perpignan to Barcelona Sants. This will bring up journeys with one change, at either Cerbère or Portbou, marked TER, R. If this method stops working for any reason, search for Perpignan to Cerbère or Portbou TER trains using int.bahn.de, then check times of the Rodalies trains from Cerbère or Portbou to Barcelona Sants at rodalies.gencat.cat/en/horaris.
Option 3, via San Sebastian at the northern end of the Pyrenees: Take a TGV from Paris or Bordeaux to Hendaye on the Spanish border, €10 fee in advance or €20 fee when the €10 fees sell out, easily bookable online as shown here. You'll also find fee-free TER regional trains from Bordeaux or Biarritz to Hendaye, no reservation necessary, just hop on and show your pass. Now take the little Euskotren metro from Hendaye to San Sebastian Amara station, this runs every 30 minutes and takes 37 minutes. It's not covered by Interrail or Eurail, but the fare is only €2.50 or so, just buy at Hendaye Euskotren station. Now take a Spanish train from San Sebastian to Madrid, Barcelona or wherever, reservation fee €10, make the reservation at the station. Check times at www.raileurope.com.

France ► Germany

TGV or ICE: Paris or Strasbourg to Mannheim, Karlsruhe, Frankfurt, Berlin, Stuttgart, Munich by TGV Duplex or ICE:
Reservation is compulsory, passholder fee €19 in 1st or 2nd class.

There's a quota for passholders which can sell out even if the train isn't full.

You can make passholder reservations at either (1) Raileurope.com as explained here, (2) using the Eurail/Interrail reservations service or (3) using the following special link to the German Railways website: int.bahn.de/en/buchung/start?KL=2&ET=PASSZUSCHLAG (leave Book seat only toggled off, select Passzuschlag Global Pass and make sure it's the €19 passholder rate). It's e-ticketed, the reservation is emailed to you.
Tip: int.bahn.de/en/buchung/start?KL=2&ET=PASSZUSCHLAG & Raileurope charge no booking fee, Eurail/Interrail adds a €2 booking fee. Raileurope allows you to request aisle/window/solo/table seating, the other two assign your seat with no choice, so I suggest using Raileurope.
Important: Do not make a normal seat-reservation for €5.20 on Paris-Germany TGVs/ICEs using int.bahn.de, as you would for other German trains. On this particular route this is not sufficient as (a) the required passholder fee is €19 and (b) you need a reservation taken from the limited quota for passholders. If you turn up with only a regular €5.20 seat reservation, you will (a) have to pay the difference and (b) if the passholder quota is sold out you may not be allowed to travel.
Eurostar (formerly Thalys): Paris to Cologne or Düsseldorf by Eurostar (formerly Thalys) high-speed train:
Passholder reservation fee: €32 in 2nd class, €37 in 1st class.
You can make passholder reservations at Raileurope.com as explained here or b-europe.com as explained here or using the official Eurail/Interrail reservations service.
Nightjet sleeper: Paris to Munich Ost by Nightjet sleeper train: See passholder prices.
Passholder reservations for Nightjet sleeper trains can be made online at the ÖBB website using Method 1, see the instructions below.

France ► Austria

Nightjet sleeper: Paris to Salzburg & Vienna by Nightjet sleeper train: See passholder prices.
Passholder reservations for Nightjet sleeper trains can be made online at the ÖBB website using Method 1, see the instructions below.

Germany

What's covered and not covered

Using a pass on trains within Germany

How to make reservations within Germany

How to make reservations on international trains from Germany to: Paris & France, Brussels & Belgium, Amsterdam & the Netherlands, Luxembourg, Switzerland, Italy, Austria, Copenhagen & Denmark, Stockholm & Sweden, Prague & Czechia, Bratislava & Slovakia, Budapest & Hungary, Slovenia & Croatia, Warsaw, Krakow & Poland.

What's covered?

Eurail & Interrail passes give unlimited travel on DB = Deutsche Bahn = German Federal Railways, int.bahn.de.

That includes all domestic local & mainline trains run by DB, including Intercity & ICE trains and (if you've a global pass) international trains to or from neighbouring countries run by DB & the partner railways in those countries including those classified EuroCity (EC) and railjet (RJ & RJX).

Passes are valid on many regional trains that have been outsourced to private operators, for a list of German operators click here.
Passes are valid on the S-Bahn suburban train networks in Berlin, Hamburg & other cities as these are run by DB (S-Bahn, not U-Bahn!).
Passes are valid on Austrian-run Nightjet trains, with a seat, couchette or sleeper reservation fee.
Passes are valid on the privately-run European Sleeper from Berlin to Amsterdam & Brussels, the SJ EuroNight sleeper from Berlin & Hamburg to Stockholm and the Snälltåget sleeper from Berlin & Hamburg to Stockholm, on payment of the relevant reservation fee.

What's not covered?

Interrail passes are not valid on privately-run lo-cost Flixtrain
Interrail passes are not valid on the Kulturzug regional train Berlin-Dresden-Wroclaw.
Interrail passes are not valid on HSB (the Harz Railway)

Help with train times

For train times within Germany see int.bahn.de.

See international train times & routes from Berlin

See international train times & routes from Munich

See international train times & routes from Cologne & Dusseldorf

See international train times & routes from Frankfurt

See international train times & routes from Hamburg

Using a pass within Germany

Intercity, ICE, railjet, EuroCity: Using a Eurail or Interrail pass in Germany is easy, as reservation is optional not mandatory on almost all German domestic daytime trains, even on fast InterCity (IC), EuroCity or high-speed InterCityExpress (ICE) trains. So you can simply hop on any train, find an empty seat and show your pass when asked.

To reserve a seat, simply make a normal seat reservation for €5.20 2nd class or €6.50 1st class using the DB (German Railways) website as explained here. You usually get to select your seat from a seat map on German ICE & IC trains.

Money-saving tip: You can reserve seats on German trains for only €3 in either class using the CD (Czech Railways) website as explained here or ÖBB (Austrian Railways) website using method 2 explained here. There are just 2 downsides: 1. You won't get seat selection on German trains if you reserve seats with CD or ÖBB, only basic options such as aisle, window, table. 2. CD & ÖBB charge a €3 fee for each train, DB charges €5.20/€6.50 for the whole journey even if it means reserving seats on multiple connecting trains, bear that in mind.

Nightjet sleeper trains:

Munich to Cologne or Düsseldorf, Berlin to Koblenz or Cologne by Nightjet sleeper train: See passholder prices.

Munich to Hamburg (or vice versa) by new generation Nightjet: See passholder prices here.
Passholder reservations for Nightjet sleeper trains can be made online at the ÖBB website using Method 1, see the instructions below.

Germany ► Paris & France

Eurostar (formerly Thalys): Cologne or Düsseldorf to Paris by Eurostar (formerly Thalys) high-speed train:
Passholder reservation fee: €32 in 2nd class, €37 in 1st class.

Passholder places limited by quota which can sell out even if the train isn't full, so book early.
You can make Eurostar passholder reservations at Raileurope.com as explained here or b-europe.com as explained here or using the official Eurail/Interrail reservations service.
TGV or ICE: Munich, Stuttgart, Berlin, Frankfurt, Karlsruhe, Mannheim to Paris by TGV or ICE:
Reservation is compulsory, passholder fee €19 in 1st or 2nd class.

There's a quota for passholders which can sell out even if the train isn't full.

You can make passholder reservations at either (1) Raileurope.com as explained here, (2) using the Eurail/Interrail reservations service or (3) using the following special link to the German Railways website: int.bahn.de/en/buchung/start?KL=2&ET=PASSZUSCHLAG (leave Book seat only toggled off, select Passzuschlag Global Pass and make sure it's the €19 passholder rate). It's e-ticketed, the reservation is emailed to you.
Tip: int.bahn.de/en/buchung/start?KL=2&ET=PASSZUSCHLAG & Raileurope charge no booking fee, Eurail/Interrail adds a €2 booking fee. Raileurope allows you to request aisle/window/solo/table seating, the other two assign your seat with no choice, so I suggest using Raileurope.
Important: Do not make a normal seat reservation for €5.20 on Germany-Paris TGVs/ICEs using int.bahn.de, as you would for other German trains. On this particular route this is not sufficient as (a) the required passholder fee is €19 and (b) you need a reservation taken from the limited quota for passholders. If you turn up with only a regular €5.20 seat reservation, you will (a) have to pay the difference, and (b) if the passholder quota is sold out you may not be allowed to travel.

Nightjet sleeper: Berlin or Munich to Paris by Nightjet sleeper train:
Passholder reservations for Nightjet sleeper trains can be made online at the ÖBB website using Method 1, see the instructions below.

Germany ► Brussels & Belgium

ICE: Frankfurt & Cologne to Brussels by ICE high-speed train:
Reservation is optional on these ICE trains. You can just hop on, sit in any empty unreserved seat & show your pass when asked. If you want to reserve seat for around €5, you can make a reservation using the German Railways website as explained here. This is a good idea as these trains can get busy.
Update: In summer from 1 June to 1 September, reservation is compulsory on these cross-border trains. If you find the German Railways website has had seat-only reservations disabled for this period, try using the Austrian Railways website (use Method 2, see the instructions here
Eurostar (formerly Thalys): Düsseldorf & Cologne to Brussels by Eurostar (formerly Thalys) high-speed train:
Passholder reservation fee: €27 in 2nd class, €32 in 1st class.

Passholder places are controlled by a quota which can sell out even if the train isn't full, so book early. You can (obviously) avoid the fee simply by using the Cologne-Brussels ICE trains instead.

You can make Eurostar passholder reservations at Raileurope.com as explained here or b-europe.com as explained here or using the official Eurail/Interrail reservations service.
European sleeper: Berlin to Antwerp & Brussels by European Sleeper overnight train:
Covered by Interrail & Eurail since July 2023. €16 for a seat, €47 for a couchette in 6-berth, €69 for a couchette in 5-berth, €99 for a bed in a 3-bed sleeper, €139 for a bed in a 2-bed sleeper or €169 for a bed in a single sleeper. Same price applies whether your pass is 1st or 2nd class.
You can make reservations at www.europeansleeper.eu by selecting Reservation Only instead of Adult in the Travel group box. booking.

Nightjet sleeper: Berlin or Munich to Brussels by Nightjet sleeper train:
Passholder reservations for Nightjet sleeper trains can be made online at the ÖBB website using Method 1, see the instructions below.

Germany ► Amsterdam & the Netherlands

Intercity trains: Berlin or Hanover to Amsterdam by Intercity (IC) train:
Reservation is optional, you can just hop on, sit in any empty unreserved seat & show your pass when asked. If you want a reserved seat, you can make a normal seat reservation using the German Railways website, as explained here.
Update: In summer from 1 June to 1 September, reservation is compulsory on these cross-border trains. If you find the German Railways website has had seat-only reservations disabled for this period, try using the Austrian Railways website (use Method 2, see the instructions here
ICE trains: Frankfurt, Cologne, Düsseldorf or Duisburg to Amsterdam by ICE train:
Reservation is normally optional, you can just hop on, sit in any empty unreserved seat & show your pass when asked. If you want a reserved seat, you can normally make a normal seat reservation using the German Railways website, as explained here.

Update: In summer from 1 June to 1 September, reservation is compulsory on these cross-border trains. If you find the German Railways website has had seat-only reservations disabled for this period, try using the Austrian Railways website (use Method 2, see the instructions here
Nightjet sleeper: Munich to Amsterdam by Nightjet sleeper train: See passholder prices.
Passholder reservations for Nightjet sleeper trains can be made online at the ÖBB website using Method 1, see the instructions below.
European Sleeper: Berlin to Amsterdam & Rotterdam by European Sleeper overnight train:
Covered by Interrail & Eurail since July 2023. €11 for a seat, €42 for a couchette in 6-berth, €64 for a couchette in 5-berth, €89 for a bed in a 3-bed sleeper, €129 for a bed in a 2-bed sleeper or €159 for a bed in a single sleeper. Same price applies whether your pass is 1st or 2nd class.
You can make reservations at www.europeansleeper.eu by selecting Reservation Only instead of Adult in the Travel group box. booking.

Germany ► Luxembourg

The regional trains from Germany to Luxembourg have no seat reservations, just hop on, sit in any empty seat & show your pass when asked.

Germany ► Switzerland

Intercity, EuroCity & ICE: Germany to Switzerland by InterCity, ICE & EuroCity trains:
Reservation is optional on all these services. You can just hop on, sit in any empty unreserved seat & show your pass when asked. If you want a reserved seat, you can make a seat reservation for around €5 using the German Railways website, as explained here.
Update: In summer from 1 June to 1 September, reservation is compulsory on these cross-border trains. If you find the German Railways website has had seat-only reservations disabled for this period, try using the Austrian Railways website (use Method 2, see the instructions here
Nightjet sleeper: Berlin, Hamburg, Düsseldorf, Cologne to Basel & Zurich by Nightjet sleeper train: See passholder prices.

Passholder reservations for Nightjet sleeper trains can be made online at the ÖBB website using Method 1, see the instructions below.

Germany ► Italy

Railjet trains from Munich to Verona, Bologna or Venice:
There is a passholder surcharge for travel on the Brenner Pass railjet trains, €10 in 2nd class or €15 in 1st class.
A reserved seat is optional, this costs an extra €3 per seat.

You can pay the surcharge and (if you want) make a seat reservation at the Austrian Railways website using Method 1, see the instructions below.
Or you can board the train without a reservation, sit in any empty unreserved seat and pay the surcharge plus an additional €5 on board the train.
Update: In summer from 1 June to 1 September, reservation is compulsory on these cross-border trains. If you find the German Railways website has had seat-only reservations disabled for this period, try using the Austrian Railways website (use Method 2, see the instructions here.
EuroCity train Frankfurt to Milan:

A passholder reservation fee must be paid for journeys on the once-daily EuroCity (EC) train from Frankfurt to Milan if crossing into Italy, €13 in both classes.

Option 1, book at Raileurope.com as explained here. It's e-ticketed, the reservation is emailed to you in minutes.

Option 2, strange as it may seem, you can make passholder reservations for this train at the Austrian Railways website www.oebb.at using method 1 explained here. There's no booking fee, but seats are assigned with no choice.

Option 3, you can also make passholder reservations using the Eurail/Interrail reservations service. There's a small booking fee. Seats are assigned with no choice. The reservation is e-ticketed and emailed to you in minutes.
Nightjet sleeper: Munich to Milan, Genoa, Venice, Bologna, Florence or Rome by Nightjet sleeper train: See passholder prices.
Passholder reservations for Nightjet sleeper trains can be made online at the ÖBB website using Method 1, see the instructions below.

Germany ► Austria

EuroCity, Intercity, ICE, railjet:
On EuroCity (EC), Intercity (IC), ICE & railjet trains from Germany to Austria, seat reservation is usually optional, if you like you can just hop on, sit in any empty unreserved seat & show your pass when asked. But reserving a seat is always a good idea for a long journey.
Update: In summer from 1 June to 1 September, reservation is compulsory on these cross-border trains, unless you're only going as far as Salzburg.
To reserve a seat, use the DB (German Railways) website as explained here or the ÖBB (Austrian Railways) website using Method 2 as explained here. It's just a normal seat reservation, the same as any fare-paying passenger would buy.
Which should you use, DB or ÖBB?
DB charge €5.20 2nd class or €6.50 1st class. ÖBB only charges €3 in either class, so ÖBB is cheaper.
However, DB lets you select your seat from a seat map on German IC and ICE trains, ÖBB only offers basic aisle, window, table options. On the other hand, ÖBB lets you select your seat from a seat map on Munich-Salzburg-Vienna railjets, while DB only offers basic aisle, window, table options. If choosing your seat is important to you, choose the right site for the right train!
BRB regional trains: Munich to Salzburg by hourly BRB regional train:
Reservation neither necessary nor possible on these regional trains, just hop on and sit anywhere you like.
Westbahn trains: Munich to Salzburg, Linz or Vienna by private operator Westbahn:
Interrail & Eurail passes give unlimited travel in standard (2nd) class on Westbahn, seat reservation optional. If you have a 1st class pass, you can either sit in a standard class seat for free or pay the upgrade to sit in a Westbahn Comfort class or First class seat.
You can reserve a seat in Standard class for €4.90 or pay for a €9.90 upgrade to Comfort or €34.90 upgrade to First with reservation included.

Go to www.westbahn.at, change DE to EN top right for English and click Reservations.
Nightjet sleeper: Germany to Austria by Nightjet sleeper train:
Düsseldorf or Cologne to Vienna or Innsbruck, Berlin to Vienna: See passholder prices.
Hamburg or Hanover to Vienna or Innsbruck by new generation Nightjet: See passholder prices here.
Passholder reservations for Nightjet sleeper trains can be made online at the ÖBB website using Method 1, see the instructions below.

Germany ► Copenhagen & Denmark

EuroCity: Hamburg to Copenhagen by EuroCity train:
Reservation is usually optional, but it's strongly recommended as these trains get very busy.
Update: In summer from 1 June to 1 September, reservation is compulsory on these cross-border trains.
You can make a seat reservation for €5.20 in 2nd class or €6.50 in 1st class using the DB (German Railways) website as explained here. If your journey involves more than one train between Germany & Denmark, you only pay one reservation fee for the whole journey.
Or for €4 per seat/train at the Danish Railways website, see the instructions here.
Or for €3 per seat/train at the Austrian Railways website using Method 2, see the instructions below.

Germany ► Stockholm & Sweden

SJ sleeper train: Berlin & Hamburg to Stockholm by SJ EuroNight sleeper train:
Reservation required. You can book passholder places in couchettes or sleepers at the Swedish Railways website www.sj.se by adding an Interrail/Eurail discount to each passenger, see the instructions for booking passholders at sj.se here.
Snälltåget sleeper train: Berlin or Hamburg to Malmö or Stockholm by Snälltåget night train:
Reservation required, €19 in a seat, €39 with a couchette.
You can make a passholder reservation online at www.snalltaget.se/en, simply tick the I have an Interrail or Eurail Pass box in the Travellers panel.

Daytime trains: Berlin to Sweden by daytime trains changing in Copenhagen: See the Germany to Denmark & Denmark to Sweden sections.

Germany ► Prague & Czechia

EuroCity trains from Berlin or Dresden to Prague
Reservation is optional on Berlin-Prague EuroCity trains, if you like you can just hop on, sit in any empty unreserved seat & show your pass when asked. However, it gets busy in summer and on Fridays & Sundays all year so I strongly recommend reserving a seat.
Update: In summer from 1 June to 1 September, reservation is compulsory on these cross-border trains.
You can make a seat reservation using either the DB (German Railways) site as explained here or the CD (Czech Railways) site as explained here.
DB charge €5.20 in 2nd class, €6.50 in 1st class. CD charge €3 in either class.
Tip: Not only is CD cheaper, they usually let you choose your seat from a seat map, DB doesn't. So it's a no-brainer to use CD!
EuroCity from Munich: Munich to Prague by EuroCity train:
Reservation is optional on this route, you can just hop on, sit in any empty unreserved seat & show your pass when asked.
Nuremberg or Frankfurt to Prague via Schwandorf or Cheb:
You can check times from Germany to Prague via these two useful routes at www.cd.cz, clicking Advanced options, then Travel via and then entering Cheb or Schwandorf in the via box. On ICE & regional trains you can just hop on, sit in any empty unreserved seat & show your pass when asked. The same goes for Czech express trains. Occasionally the Cheb-Prague connection is a CD SuperCity (SC) trains, reservation compulsory, €7 fee.

Germany ► Bratislava & Slovakia

EuroCity train: Berlin or Dresden to Bratislava by EuroCity train Hungaria:
Reservation is optional on this train, you can just hop on, sit in any empty unreserved seat & show your pass when asked. However, it can get very busy in summer and on Fridays & Sundays all year so I'd strongly recommend reserving a seat.

You can make a normal seat reservation for €3 to €5 using either the German Railways website as explained here or the Czech Railways website as explained here.
Update: In summer from 1 June to 1 September, reservation is compulsory on these cross-border trains.

Sleeper from Berlin: Berlin to Bratislava by EuroNight sleeper train:
Couchette in 6-berth €44, couchette in 4-berth €54, bed in 3-bed sleeper €69, in 2-bed €94, in single-bed €169, all accommodation types can be booked with a 2nd class pass.

Passholder reservations for sleepers or couchettes can be made online at the ÖBB website using Method 1, see the instructions below.

Germany ► Budapest & Hungary

EuroCity train: Berlin or Dresden to Budapest by EuroCity train Hungaria:
Reservation is optional on this train, you can just hop on, sit in any empty unreserved seat & show your pass when asked. However, it can get very busy in summer and on Fridays & Sundays all year so I'd strongly recommend reserving a seat.

You can make a normal seat reservation for €3 to €5 using either the German Railways website as explained here or the Czech Railways website as explained here.
Update: In summer from 1 June to 1 September, reservation is compulsory on these cross-border trains.
Railjet trains: Munich to Budapest by railjet train:
Reservation is optional on this route, you can just hop on, sit in any empty unreserved seat & show your pass when asked. If you want a reserved seat, you can make a normal seat reservation for around €5 using the German Railways website as explained here.
Update: In summer from 1 June to 1 September, reservation is compulsory on these cross-border trains.
Sleeper from Berlin: Berlin to Budapest by EuroNight sleeper train:
Couchette in 6-berth €44, couchette in 4-berth €54, bed in 3-bed sleeper €69, in 2-bed €94, in single-bed €169, all accommodation types can be booked with a 2nd class pass.

Passholder reservations for sleepers or couchettes can be made online at the ÖBB website using Method 1, see the instructions below.
Sleeper from Stuttgart or Munich: Stuttgart or Munich to Budapest by EuroNight sleeper train:
Couchette in 6-berth €44, couchette in 4-berth €54, bed in 3-bed sleeper €69, in 2-bed €94, in single-bed €169, all accommodation types can be booked with a 2nd class pass.

Passholder reservations for sleepers or couchettes can be made online at the ÖBB website using Method 1, see the instructions below.

Germany ► Slovenia & Croatia

Day trains: Munich to Ljubljana & Zagreb by daytime train:
Reservation optional, you can just get on and sit in any empty unreserved seat and show your pass when asked. If you want a reserved seat, you can make a normal seat reservation for around €5 using the German Railways website as explained here.
Update: In summer from 1 June to 1 September, reservation is compulsory on these cross-border trains.
Sleeper trains: Stuttgart or Munich to Ljubljana or Zagreb by EuroNight sleeper train:
Couchette in 6-berth €29.90, couchette in 4-berth €34.90, bed in 3-bed sleeper €64.90, in 2-bed €109.90, in single-bed €234.90.

Prices vary slightly according to demand. All types of couchette or sleeper can be booked with any class of pass.

Passholder reservations for sleepers or couchettes can be made online at the ÖBB website using Method 1, see the instructions below.

Germany ► Poland

EuroCity trains: Berlin to Warsaw, Krakow, Gdansk or Gdynia by EuroCity train:
Reservation is compulsory, €5.20 in 2nd class, €6.50 in 1st class if you use DB or only €4 if you reserve using PKP.

You can make a seat reservation using the DB (German Railways) site as explained here and print it out or show it on your phone.

Or use the PKP Intercity (Polish Railways) website as explained here, also printing it out or showing it on your phone
Regional trains: Berlin to Stettin & other cross-border regional trains:
Seat reservations neither necessary nor possible, just hop on the train and show your pass when asked.

Great Britain

What's covered?

Eurail & Interrail passes give unlimited travel on all 20+ train operators which make up National Rail, www.nationalrail.co.uk, including LNER, Avanti West Coast, Great Western, ScotRail, Transport For Wales Trains, South Western Railways and so on
Passes don't cover Transport for London's London Underground, buses or trams. But they do cover London Overground and the National-Rail-run Elizabeth Line.
Passes do not cover the Heathrow Express premium fast trains between Heathrow and London Paddington.

But they do cover the Elizabeth Line stopping trains between Heathrow and London Paddington on exactly the same route.

If you live in the UK, remember the 2-day limit on using an Interrail pass in your home country.

Help with train times

About train travel in Britain

About Eurostar from London to Paris & Brussels

About Eurostar from London to Amsterdam

See train times & routes from London to mainland Europe

Using a pass in Britain

Sleeper trains to/from Scotland & Cornwall

There are just two services in Britain where reservation is compulsory for all passengers including passholders (but read the All other trains in Britain paragraph below), namely the Caledonian Sleeper between London & Scotland and GWR's Night Riviera sleeper between London & Cornwall.

To use a sleeper berth between London & Scotland or London & Cornwall you need to pay the sleeper berth supplement.

See the Caledonian Sleeper page for prices & how to make a sleeper reservation to/from Scotland online.

See the Sleeper to Cornwall page for prices & how to make a sleeper reservation to/from Cornwall (this cannot be done online).

A seat reservation on these sleeper trains is free, if you're happy with a seat not a bed.
All other trains

Reservation on all other trains in Britain is either unnecessary (suburban & local trains) or optional (longer-distance trains). You can just get on any train, find any empty unreserved seat and sit in it, showing your pass when asked.

However, several train operators are shown on the official Interrail & Eurail websites as mandatory reservation even though they are not compulsory-reservation for normal ticket holders. The list used to include a dozen operators, I'm glad to see it's been shortened to just a few:

LNER (London-York-Leeds/Newcastle-Edinburgh & branches), TransPennine Express (Liverpool-Manchester-York/Leeds-Newcastle & branches) and Avanti West Coast (London to Birmingham, Manchester, Liverpool, Holyhead, Carlisle & Glasgow)

The Man in Seat 61 says: "In fact, these operators' trains are NOT 'mandatory reservation' at all for normal ticket holders, this is just Rail Delivery Group being over-the-top. Feedback suggests you'll be fine getting on without a reservation, I doubt conductors know or care. However, a reserved seat for a long journey is recommended, especially on Friday or Sunday afternoons or morning peak periods. I have so far had one correspondent say they travelled extensively on these operators without making any reservations at all, the conductors never worried about it, just as I expected. So make a free seat reservation if you can, but don't worry about it if you can't." Feedback appreciated.

In fact, the information on travel in Great Britain on www.myinterrail.co.uk - which is managed by National Rail, who ought to know - differs from that on the Interrail & Eurail website, it confirms that no reservations are compulsory on any British domestic train, other than sleepers.

How to make reservations free-of-charge

Do not pay £££ to make seat reservations through an agency or even via the Interrail/Eurail reservation service. There's a well-hidden way to make stand-alone seat reservations for free to go with an Interrail or Eurail pass:

1. Go to www.gwr.com & register for an account.

2. Sign in & click My account.

3. Click Bookings.

4. Click Make a seat/bike reservation.

5. Run an enquiry and select the train you want.

It will ask you to select a fare, select any fare in the right class, it doesn't matter what fare type you click on, continue and make the reservation. It says you won't be charged and you'll get a free seat reservation without the need to enter any payment details.

6. Your reservation details with car number & seat number will appear on the screen.
You don't get (and don't need) any reservation ticket, simply make a note of the car & seat numbers or take a screenshot, although you should get an email confirming them. Then board the train and sit in those seats. The conductor won't ask you for any proof of reservation, but you (obviously) need to know where your reserved seat is and you might want to show proof if you found someone sitting in your seat.
This process works for any train, route or operator where seat reservations are possible, including GWR, LNER, Avanti West Coast, East Midlands Trains, Cross-Country, TransPennine & Scotrail. Please let me know if this process changes, or ceases to work.
Tip: If you want a seat reservation on an LNER train (for example, between London & York, Leeds, Newcastle, Edinburgh) you can also use www.lner.co.uk/travel-information/make-a-reservation to make a free seat reservation to go with a pass, up to 5 minutes before the train leaves its starting station. You can choose your seat from a seat map on LNER trains if you reserve this way. You'll need to register for an LNER account during the process, but no payment is necessary, it's free just like gwr.com. However, gwr.com can reserve seats on any operator, this LNER system can only make reservations on LNER trains.
In person: Simply ask at any staffed station any time up to about 2h before departure, or ideally the day before. There are always places available, even on the day.

Using a pass on Eurostar to Paris, Brussels & Amsterdam

London to Lille, Paris or Brusselsby Eurostar:

Eurostar can be used from London to Lille, Paris or Brussels if you pay a special passholder fare of €35 in Standard or (if you have a 1st class pass) €40 in Plus.

You can buy Eurostar passholder tickets online as explained here.
London to Rotterdam or Amsterdam by Eurostar:

Eurostar can be used from London to Rotterdam or Amserdam if you pay a special passholder fare of €35 in Standard or (if you have a 1st class pass) €43 in Plus.

You can buy Eurostar passholder tickets online as explained here.

Greece

What's covered?

Eurail & Interrail passes give unlimited travel on Hellenic Train (Greek national railways, www.hellenictrain.gr, formerly TrainOSE). That includes all domestic local & mainline trains run by Hellenic Train and (if you've a global pass) international trains to or from North Macedonia, Serbia & Bulgaria run by Hellenic Train & the partner railways SZ (Serbia), MK (North Macedonia) & BDZ (Bulgaria), if and when running.

Help with train times

See train times & routes from Athens

Using a pass on Greek trains

InterCity trains including most Athens -Thessaloniki trains:

Reservation compulsory, it's free. Cannot be done online, just make a reservation at any main station, there are usually places available on most trains even on the day.

Using a pass on international trains

The supplement for a couchette on the Thessaloniki-Belgrade train (if and when running) is around €8.

Using a pass on the ferries to Italy

Eurail & Interrail passes give 'free passage' on Blue Star & Superfast (Attica Group) ferries, Bari-Igoumenitsa-Corfu-Patras, Ancona-Igoumenitsa-Corfu-Patras.

However, you still have to pay port taxes, fuel surcharge & high season supplement, so expect to pay €29-€44 depending on the season.

2nd class passes allow travel with a 'deck-lounge' place, meaning a place on the ferry but with no specific seat or berth. You can use the seating in the lounge and there's space under cover on deck to use a sleeping-bag if you have one, many backpackers do this.

1st class passes include travel with a reserved aircraft-type reclining seat. Or you can pay extra for one if you have a 2nd class pass.

You can pay extra for a berth or cabin. A bed in a shared single-gender cabin starts at around €131, a private cabin with shower & toilet starts at around €270. There's no discount on the cabin.
Book the ferry online at www.superfast.com.
For a one-way trip, click inside the return date field and look for the one-way trip toggle.
Enter your type & class of Interrail or Eurail pass in the discount box.
Select aircraft type seat or deck -lounge, or add a cabin berth or whole cabin.
Pre-booking is recommended in summer as the route gets busy.

Hungary

What's covered?

Eurail & Interrail passes give unlimited travel on MAV = Hungarian State Railways, www.mav-start.hu. That includes all domestic local & mainline trains run by MAV and (if you've a global pass) international trains to or from neighbouring countries run by MAV & the national railways in those countries.
They also cover GySev, a private operator of regional trains in part of Hungary, www.gysev.hu.
Passes also cover private operator Regiojet, who run a handful of Budapest-Vienna-Prague trains in competition with the national operators.

Help with train times

For train times within Hungary, see www.mav-start.hu.

See international train times & routes from Budapest

Using a pass within Hungary

You can travel on local or regional trains without any reservation, just hop on and show your pass when asked.
Reservation is compulsory for domestic journeys on InterCity (IC), EuroCity (EC) & railjet (RJ or RJX) trains, €0.750 to €2.50 fee per seat. This is a normal seat reservation as for any ticket holder.
To make seat reservations without any booking fee, use the MAV app or the MAV website jegy.mav.hu (click EN for English). You do this by clicking Passengers and discounts and adding the discount International pass, ticket or global price to each passenger. This gives 100% discount on the fare, leaving just the reservation fee.

Hungary ► Austria

EuroCity & railjet: Budapest to Vienna, Salzburg, Innsbruck by railjet, EuroCity or express train:
Reservation is optional, you can hop on any train, sit in any empty unreserved seat and show your pass when asked. However, reserving a seat is a good idea, especially in summer or at other busy times.
You can make a seat reservation for around €3 at the Austrian Railways website using Method 2, see the instructions here.
Regiojet: Budapest to Vienna by Regiojet train:
Seat reservation required, €1.3 in Low Cost, €2 in Standard, €2.8 in Relax or (only if you have a 1st class pass) €1.3 in Business.
Regiojet passholder reservations can be made online at www.regiojet.com: Use the journey planner as if buying a normal ticket. When prices appear, look for the Only seat reservations toggle and use it. Select the train you want, then under Type of ticket purchased select Interrail & Eurail. You print out your reservation or can show it in the Regiojet app.
Alternatively, approach staff on the train before departure.

Hungary ► Germany

EuroCity trains: Budapest to Dresden or Berlin by EuroCity train
Reservation is optional, you can hop on the train, sit in any empty unreserved seat and show your pass when asked. If you want a reserved seat, you can make a normal seat reservation for around €4.50 at the German Railways website, see the instructions here.
Update: In summer from 1 June to 1 September, reservation is compulsory on these cross-border trains. If you find the German Railways website has had seat-only reservations disabled for this period, try using the Austrian Railways website (use Method 2, see the instructions here

Railjet trains: Budapest to Munich by railjet train
Reservation is optional, you can hop on any train, sit in any empty unreserved seat and show your pass when asked. If you want a reserved seat, you can make a seat reservation for around €3 at the Austrian Railways website using Method 2, see the instructions here.
Update: In summer from 1 June to 1 September, reservation is compulsory on these cross-border trains.

Sleeper train: Budapest to Munich by EuroNight sleeper train
Couchette in 6-berth €44, couchette in 4-berth €54, bed in 3-bed sleeper €69, in 2-bed €94, in single-bed €169, all accommodation types can be booked with a 2nd class pass.

Passholder reservations for sleepers or couchettes can be made online at the ÖBB website using Method 1, see the instructions below.

Sleeper train: Budapest to Berlin by EuroNight sleeper train
Couchette in 6-berth €44, couchette in 4-berth €54, bed in 3-bed sleeper €69, in 2-bed €94, in single-bed €169, all accommodation types can be booked with a 2nd class pass.

Passholder reservations for sleepers or couchettes can be made online at the ÖBB website using Method 1, see the instructions below.

Hungary ► Switzerland

Sleeper train: Budapest to Zurich by EuroNight sleeper train
Couchette in 6-berth €44, couchette in 4-berth €54, bed in 3-bed sleeper €69, in 2-bed €94, in single-bed €169, all accommodation types can be booked with a 2nd class pass.

Passholder reservations for sleepers or couchettes can be made online at the ÖBB website using Method 1, see the instructions below.

Hungary ► Slovakia & Czechia

EuroCity train: Budapest to Bratislava & Prague by EuroCity train
Reservation is optional, you can hop on any train, sit in any empty unreserved seat and show your pass when asked. However, it's a good idea to reserve a seat especially in summer or at other busy times.
You can reserve a seat for around €3 at the Czech Railways site, see the instructions here.
Sleeper train: Budapest to Prague by sleeper train
€21 for a bed in a 3-berth sleeper, €31 for a bed in a 2-bed sleeper, €72 in a single-bed sleeper, all bookable with a 2nd class pass. More about the Budapest to Prague sleeper train.
Passholder reservations for Budapest to Prague sleeper berths can be made at the Czech Railways website www.cd.cz, with no added booking fee. Before running the enquiry, click where it says 1 x Adult 26-64 No discount card then click on No discount card , click Interrail and Eurail Pass then select the one you have. You print your own ticket or can show it on your phone.
Regiojet: Budapest to Prague by privately-run Regiojet train
Seat reservation required, €1.3 in Low Cost, €2 in Standard, €2.8 in Relax or (only if you have a 1st class pass) €1.3 in Business.
Regiojet passholder reservations can be made online at www.regiojet.com: Use the journey planner as if buying a normal ticket. When prices appear, look for the Only seat reservations toggle and use it. Select the train you want, then under Type of ticket purchased select Interrail & Eurail. You print out your reservation or can show it in the Regiojet app. Alternatively, approach staff on the train before departure.

Hungary ► Romania

Day trains: Budapest to Bucharest & Romania by daytime train:
Seat reservation is optional, if you want a reserved seat it costs €3. Make the reservation at the station or phone an agency. It cannot be made online.
Sleeper trains: Budapest to Bucharest by sleeper train:
Couchette in 6-bunk compartment €13.40, 4-bunk couchette €20, berth in 3-berth sleeper €28, berth in 2-berth sleeper €42. Bed in single-bed sleeper (requires 1st class pass) €98.
Option 1, you can book using the Interrail/Eurail reservation service as explained here. The reservation is emailed to you and you print it out.
Option 2, you can also make reservations on all these sleeper trains using the Hungarian Railways website as explained below. This way you pay no booking fee. You print out the reservation

Hungary ► Poland

EuroCity trains: Budapest to Krakow or Warsaw by EuroCity train
Seat reservation is compulsory and costs around €3. It's just a normal seat reservation as any regular passenger would need.
You can (surprisingly, perhaps) make a seat reservation at the CD (Czech Railways) website, see the instructions here.
Or you can make a seat reservation at the ÖBB (Austrian Railways) website using Method 2, see the instructions here.
Sleeper train: Budapest to Krakow or Warsaw by EuroNight sleeper train:
€17 for a couchette in a 6-bunk couchette, €32 for a bed in a 3-berth sleeper, €44 for a bed in a 2-bed sleeper, €83 in a single-bed sleeper, all bookable with a 2nd class pass.
You can (surprisingly, perhaps) make a seat reservation at the CD (Czech Railways) website, see the instructions here.

Hungary ► Slovenia

Budapest to Ljubljana by direct train:
Seat reservation is compulsory, €3 per seat.
It's just a normal seat reservation which can be made at the CD (Czech Railways) website, see the instructions here.

Hungary ► Croatia

Budapest to Zagreb by direct train:
Seat reservation is compulsory, €3 per seat. It's just a normal seat reservation which can be made using using the Austrian Railways website (use Method 2, see the instructions here or at the CD (Czech Railways) website, see the instructions here.

Ireland

What's covered?

Eurail & Interrail passes give unlimited travel on IE = Iarnrod Eireann, Irish republic railways, www.irishrail.ie.
Passes cover Translink trains in Northern Ireland and the cross-border Enterprise trains between Dublin & Belfast.

Other pass benefits

30% discount on Stena Line (www.stenaline.co.uk) Ireland-UK ferries (Dublin-Holyhead, Rosslare-Fishguard, Belfast-Cairnryan)
30% discount on Irish Ferries (www.irishferries.com) Ireland-UK & Ireland-France ferries (Dublin-Holyhead, Rosslare to Cherbourg & Roscoff, Rosslare to Pembroke). You cannot book online with this discount, but call them and it can be done over the phone or at the port.

Using a pass on Irish trains

Seat reservation is neither necessary nor possible on local & suburban trains including DART trains in the Dublin area and Translink trains running wholly within Northern Ireland. You can just hop on and show your pass when asked.
Seat reservation is optional but recommended on Iarnrod Eireann inter-city trains and Dublin-Belfast Enterprise trains.

You can make a standard class seat reservation on these trains using www.irishrail.ie.

On their home page, click where it says 1 passenger, set Adults to 0 and set Reservation only to however many seats you want.

A standard class reservation is free on some trains, €2.50 on busy trains.

If you see a first class 'reservation' price between €10 and €20 on Dublin-Belfast & Dublin-Cork trains (the only Irish trains which have 1st class), this is in fact an upgrade to 1st class including 1st class seat reservation, NOT a seat reservation alone. You can buy this with a 2nd class Interrail or Eurail pass to upgrade to 1st class.

If you have a 1st class pass, it is not possible to make a 1st class seat reservation online without paying €10-€20 for an upgrade you don't need, so make seat reservations at any staffed Irish station.

You download your reservation ticket or can collect a reservation ticket at the station from a ticket machine.

For train times see www.irishrail.ie.

Using a pass on international trains

Seat reservation is optional on the Dublin-Belfast Enterprise trains. If you want a reserved seat, do this at any Irish station when you get there.

Italy

What's covered?

Eurail & Interrail passes give unlimited travel on Trenitalia = Italian State Railways, www.trenitalia.com.

That includes all of Trenitalia's domestic regionale (R), regionale veloce (RV), Intercity (IC), Intercity Notte (ICN), EuroCity, Frecciarossa, Frecciargento, Frecciabianca trains. It also includes Leonardo Express trains between Fiumicino airport and Rome.
If you've a global pass, it also includes almost all international trains to/from Italy including:

EuroCity (EC) trains to/from Switzerland run by Trenitalia/SBB, the Munich-Innsbruck-Italy EC/RJ trains run by DB/ÖBB, Nightjet sleeper trains between Italy and Vienna/Salzburg/Munich/Stuttgart, various regional trains Italy-Switzerland, Italy-Austria, Italy-Slovenia, the Trieste-Ljubljana-Vienna EuroCity train run by ÖBB, and the Milan-Turin-Paris TGVs run by SNCF (but not the competing Milan-Turin-Paris Frecciarossas).

Passes give unlimited travel on Trenord, a consortium of Trenitalia & LeNord which runs regional trains north of Milan including Milan-Tirano, www.trenord.it. However, Trenord's Lecco-Piona trains and trains to/from Malpensa Airport aren't covered.
Passes give unlimited travel on some independent regional trains including FART, MICOTRA, TILO, Ferrovienord.

What's not covered?

Eurail & Interrail passes don't cover Italo high-speed trains run by private operator NTV which compete with Trenitalia on the main Turin/Milan/Venice-Florence-Rome-Naples route. Simply use Trenitalia instead.
Eurail & Interrail passes don't cover Trenitalia's international Frecciarossa train between Paris, Lyon, Turin & Milan, because when in France it's run by Trenitalia France which not a signatory to the Interrail/Eurail scheme, even though it's subsidiary of Trenitalia. However, passes cover the competing French Railways TGV which operates on the same Paris-Turin-Milan route, reservation required.
Eurail & Interrail passes also don't cover:

The Circumvesuviana Railway Naples-Pompeii-Sorrento, but this costs only a few euros anyway.

Trains run by SAD between Fortezza and San Candido (connecting for Lienz & Austria).

Trains between Malpensa airport and Milan.

Trains run by Ferrovia Circumetnea in the mount Etna area.

Trains run by Ferrovie del Sud Est (FSE) in the Bari & Lecce area, even though it's now a Trenitalia subsidiary.

A couple of regional lines out of Arezzo run by independent regional operator TFT.

Help with train times

For train times within Italy use www.trenitalia.com.

See international train times & routes from Rome

See international train times & routes from Florence

See international train times & routes from Venice

See international train times & routes from Milan

See international train times & routes from Naples

See international train times & routes from Pisa

See international train times & routes from Cinque Terre

Using a pass within Italy

Frecciarossa, Frecciargento, Frecciabianca

Reservation required. A €13 passholder reservation fee applies to all Frecciarossa, Frecciargento & Frecciabianca trains linking Milan, Florence, Rome, Naples, Venice, Verona, Turin. It's per trip, so two connecting trains = 2 x €13.
InterCity (IC) trains

Reservation required, a €3 passholder reservation fee applies.
Intercity Notte (ICN) sleeper trains

With any class of pass (1st or 2nd), a couchette in 4-berth costs €41, bed in 3-bed sleeper €48, bed in 2-bed double sleeper €58, single bed sleeper €122. All per person per bed. Superior sleepers with shower/toilet (only on a few routes) can also be booked, double €58, single €122.

Tip: Before booking a couchette or sleeper in Italy with your pass, first check point-to-point sleeper fares at www.trenitalia.com. For example, I've just booked a sleeper from Palermo to Naples in 6 weeks time for €87 (limited-availability super-economy fare with single-bed sleeper included), which is cheaper than paying the €122 passholder reservation fee for a single sleeper. Even if you had already bought a pass, it would be cheaper not to use it! But as Italian fares are dynamic, it depends what fares you see on your date.

Regional trains

Reservations are not required and not even possible on regional trains (Regionale & Regionale Veloce, R & RV). You simply get on, sit in any empty seat and show your pass when asked.

How to make reservations for Italy

You cannot make passholder reservations at Trenitalia.com. Instead, choose from one of these methods:
Option 1, use Raileurope.com as explained here - recommended

This is the best way to make passholder reservations for Trenitalia, because (a) at the time I write this they don't charge a booking fee and (b) you can select specific seats from a seat map.

Raileurope is currently the only seller of passholder reservations that allows you to select seats on Italian trains, seat selection is optional and costs an extra €2, the same as when buying a normal ticket.

You need to use the Raileurope desktop site to get the seat selection function. On a phone, use the Request desktop site function.

Raileurope can reserve seats on all Trenitalia high-speed trains, Intercity trains and sleepers (but for some reason, not couchettes) on Intercity Notte sleeper trains. It's e-ticketed, the reservation is emailed to you within minutes.
Option 2, use oebb.at

Strange as it may seem, you can make passholder reservations online for Italian daytime trains at the ÖBB (Austrian Railways) website shop.oebbtickets.at and they don't charge a booking fee, just the cost of the reservation. It works for Italian high-speed & InterCity trains, but not for sleepers or couchettes on night trains. There is no seat choice, seats are assigned.

Go to Austrian Railways shop.oebbtickets.at and set up an enquiry for the Italian journey you want, for example from Rome to Florence.

Where it says 1 x adult, click change.

Now click Add discount and run a search for Interrail or Eurail. Select Interrail / Eurail - Globalpass and confirm.

Do not tick the Seat reservation only box, as technically you're booking a special passholder fare here, not a seat reservation.

Now run the enquiry by clicking the Find button.

You should see €13 passholder reservations on high-speed trains and €3 reservations on Intercity trains.

If it says Ticket not available, you may have ticked the Seat reservation only box in error, re-run with the box un-ticked!

Go ahead and buy! You print out your reservation. Do let me know if this method stops working.
Option 3, use Italiarail.com

Go to partners.italiarail.com/default?force_pass=true and use the journey planner. You will see passholder prices in the search results.

It can book daytime trains, 4-berth couchettes & 2 or 3 bed sleepers, but for some reason won't book single-bed sleeper (so use Raileurope!).

They charge the official reservation fee plus a €3.50 booking fee per reservation.

Seats are assigned without choice, but Italiarail show you your seat numbers before you pay, so when booking a 1st/business class seat on a Frecciarossa for example, you can see whether you're getting a seat number ending in A, B or D, where A and B are two-abreast seats on one side of the aisle, D is a solo seat on the other side which is both aisle and window. When travelling solo, I naturally want a seat ending in D! You can compare the seats it proposes with the relevant seat map here, and re-run the enquiry until you get seats you like. Not exactly state-of-the-art seat selection, but better than the methods which don't show you seat numbers until after you pay.

Tip: If it won't accept a mobile pass number, simply generate a old-school pass cover number from your mobile pass number using this special page: www.eurail.com/en/book-reservations#/generatePassCoverNumber.

Option 4, using the Eurail/Interrail reservations service

You can make passholder reservations for Italian high-speed & InterCity trains using the Eurail/Interrail reservations service, the reservation is e-ticketed and emailed to you. There's a €2 booking fee in addition to the cost of the reservation. There's no seat choice, seats are assigned.

The Eurail/Interrail reservations service can also make reservations for sleepers & couchettes on InterCity Notte trains, but there's a problem. If you have a 2nd class pass it only offers couchettes, even though you're entitled to book single or double sleepers with a 2nd class pass. So if you have a 2nd class pass and want to book a single or double sleeper, use option 3 below.

Option 5, make reservations at stations

You can make passholder reservations at any staffed Italian station, but you'll need to use the staffed counter, the self-service machines don't sell passholder reservations.

Tip: To make a passholder reservation on a Trenitalia Frecce or Intercity train leaving in the next hour or so, go to one of the little mobile Last Minute desks (servizi last minute) on the concourse near the platforms (see the photo below). Much quicker than queuing at the ticket office!

Booking couchettes or sleepers on InterCity Notte

You can book 1, 2 & 3 bed sleepers (but not couchettes) using Raileurope. You can book 4-berth couchettes and 2 or 3 bed sleepers (but not single sleepers) using italiarail.com. If you have any problems, here are two other methods:

Option 6, email andy@railtravelcentre.com, the same expert that runs www.discoverbyrail.com. He can arrange passholder bookings for Italian sleeper trains including single or double sleepers whatever class of pass you have. Tickets can be posted to you or he can email the booking reference which is in fact all you need.

Option 7, call SBB (Swiss Railways) on +41 848 44 66 88, lines open 24/7. They have phone lines that speak French, German, Italian and English. They can book it for you and email you the reservation. Feedback appreciated!

Italy ► Switzerland

EuroCity trains: Venice, Genoa or Milan to Geneva, Zurich, Basel, Bern, Luzern etc. by EuroCity train:

Reservation required, a passholder reservation fee applies, €13 in both classes.

Option 1, using Raileurope.com as explained here. Raileurope is top choice as (a) at the time I write they add no booking fee and (b) you can choose your seats from a seat map. No other retailer offers this! The reservation is e-ticketed and emailed to you in minutes.

Option 2, strange as it may seem, you can make passholder reservations for these Italy-Switzerland EuroCity trains at the Austrian Railways website oebb.at using method 1 explained here. There's no booking fee. However, seats are assigned with no choice.

Option 3, you can also make passholder reservations online using the Eurail/Interrail reservations service. There's a small booking fee. Seats are assigned with no choice. The reservation is e-ticketed and emailed to you in minutes.

To avoid the need for reservations you can use regional trains from Milan to Domodossola or Lugano, for example take the hourly TILO regional express from Milan Centrale to Lugano, then use a Swiss domestic train to Zurich. It's just a little slower and less comfortable.
Regional trains, for example Locarno-Lugano-Milan or Brig-Domodossola-Milan

No reservation necessary or even possible on regional trains (marked R or RE in timetables), just hop on, sit anywhere and show your pass when asked.

Bernina route: Milan, Varenna, Lecco to Tirano, St Moritz, Chur & Zurich via the amazingly scenic Bernina route:

No reservation is needed on the two-hourly Italian regional trains from Milan Centrale to Tirano, just hop on and show your pass. No reservation needed on the hourly Swiss local trains from Tirano to St Moritz or on the connecting Swiss trains to Chur & Zurich. Only if you choose to use the special Tirano-Chur Bernina Express panoramic tourist train is a seat reservation compulsory, this can be made online as shown here.
Centovalli Railway (FART): Domodossola-Locarno.

Passes are valid on the beautifully scenic Centovalli Railway, but a €1.50 supplement must be paid at the station before boarding. Reservation is optional (but recommended), this costs €4 and can be made online at prenota.vigezzinacentovalli.com. Select Seat reservation and then (as Interrail/Eurail is not specifically listed in their drop-down box) select Swiss Pass as your ticket type.

Italy ► Paris, Nice, France

TGV: Milan or Turin to Paris by TGV
A passholder reservation fee must be paid, a hefty €31 in 2nd class, €45 in 1st class. You can make passholder reservations online at Raileurope.com as explained here or using the Eurail/Interrail reservations service. The reservation is e-ticketed and emailed to you in minutes.
Passholder places are quota-controlled, so can run out even if the train has plenty of seats left. If booking well in advance it may be cheaper to buy a normal ticket, as these start at just €29 2nd class, €46 in 1st class including reservation if you pre-book at www.raileurope.com or www.thetrainline.com.
Frecciarossa: Milan or Turin to Paris by Frecciarossa
Passes aren't currently valid on Trenitalia's Milan-Paris Frecciarossas, because when in France they are run by Trenitalia France which is not a signatory to the Interrail & Eurail schemes, even though it is a subsidiary of Trenitalia. But advance-purchase fares for the Frecciarossa can be cheaper than the TGV passholder fee, so check normal prices using www.italiarail.com, www.raileurope.com or www.thetrainline.com.
Regional trains: Italy to Monaco, Nice & Cannes via Ventimiglia:
The direct Milan-Genoa-Nice Thello trains were discontinued in July 2021, but you can still travel between Italy & Nice using Italian domestic trains to Ventimiglia on the French border, then French domestic TER local trains from Ventimiglia to Monte Carlo, Nice & Cannes, see the Nice to Italy by train page. Normal reservation arrangements & fees apply to Trenitalia's Intercity & Frecciabianca trains from Milan & Genoa to Ventimiglia, see the Italy national trains section below. No reservation is needed for the French TER trains from Ventimiglia to Nice, nor if you use an Italian regional train from Genoa to Ventimiglia.

Italy ► Austria & Germany

Railjet trains to Innsbruck & Munich: Venice, Bologna, Verona to Innsbruck & Munich by railjet train on the Brenner route.
There is a passholder surcharge for travel on these Brenner Pass railjet trains, €10 in 2nd class or €15 in 1st class.
A reserved seat is optional, this costs an extra €3 per seat.

You can pay the surcharge and (if you want) make a seat reservation at the Austrian Railways website using Method 1, see the instructions below.
Or you can board the train without a reservation, sit in any empty unreserved seat and pay the surcharge plus an additional €5 on board the train.
Update: In summer from 1 June to 1 September, reservation is compulsory on these cross-border trains.
Railjet trains to Vienna: Venice to Villach & Vienna by railjet train
There is a passholder surcharge for travel on these Venice-Vienna railjet trains, €10 in 2nd class or €15 in 1st class.
A reserved seat is optional, this costs an extra €3 per seat.

You can pay the surcharge and (if you want) make a seat reservation at the Austrian Railways website using Method 1, see the instructions below.
Or you can board the train without a reservation, sit in any empty unreserved seat and pay the surcharge plus an additional €5 on board the train.
EuroCity train Milan to Frankfurt:
Reservation compulsory for journeys from Italy, a passholder reservation is €11 in 2nd class, €13 in 1st class for passholders. You can make passholder reservations online using the Eurail/Interrail reservations service, the reservation is e-ticketed and emailed to you in minutes.
EuroCity train Trieste to Vienna (via Slovenia):
There is a small passholder surcharge for travel on the part within Italy, €2.60 in 2nd class, €4.60 in 1st class.
Seat reservation is optional for an extra €3 per seat.
You can make a seat reservation & pay the surcharge at the Austrian Railways website using Method 1, see the instructions below.
Nightjet sleeper: Rome, Florence, Genoa, Milan or Venice to Munich, Salzburg or Vienna by Nightjet sleeper train: See passholder prices.
Passholder reservations for Nightjet sleeper trains can be made online at the ÖBB website using Method 1, see the instructions below.

Italy ► Slovenia

Regional trains Trieste-Ljubljana: No reservation necessary or possible, hop on, sit anywhere, show your pass when asked.
EuroCity train Trieste-Ljubljana: There is a small passholder surcharge for the part within Italy, €2.60, but seat reservation is optional.
You can board the train without a reservation, sit in any empty unreserved seat and pay the surcharge on board when the conductor comes round, or you can make a seat reservation & pay the surcharge at the Austrian Railways website using Method 1, see the instructions below.

Italy ► Greece by ferry

Eurail & Interrail passes give 'free passage' on Blue Star & Superfast (Attica Group) ferries Bari-Igoumenitsa-Corfu-Patras, Ancona-Igoumenitsa-Corfu-Patras.

However, you still have to pay port taxes, fuel surcharge & high season supplement, so expect to pay €29-€44 depending on the season.

2nd class passes allow travel with a 'deck-lounge' place, meaning a place on the ferry but with no specific seat or berth. You can use the seating in the lounge and there's space under cover on deck to use a sleeping-bag if you have one, many backpackers do this.

1st class passes include travel with a reserved aircraft-type reclining seat. Or you can pay extra for one if you have a 2nd class pass.

You can pay extra for a berth or cabin. A bed in a shared single-gender cabin starts at around €131, a private cabin with shower & toilet starts at around €270. There's no discount on the cabin.
Book the ferry online at www.superfast.com.
For a one-way trip, click inside the return date field and look for the one-way trip toggle.
Enter your type & class of Interrail or Eurail pass in the discount box.
Select aircraft type seat or deck -lounge, or add a cabin berth or whole cabin.
Pre-booking is recommended in summer as the route gets busy.

Latvia

What's covered?

Eurail & Interrail passes give unlimited travel on all trains run by Latvian railways, www.pv.lv.

Other pass benefits

Special fares on Tallink-Silja Line ferries Stockholm-Riga.

Help with train times

For trains within Latvia, see www.pv.lv.

See international train & ferry times & routes from Riga.

Using a pass on national trains

Reservations aren't needed, just hop on and show your pass. But prices are incredibly cheap, don't buy a pass for Latvia before checking normal train fares.

Using a pass on international trains

Passes cover the Riga-Vilnius train, seat reservation required, €5 in either class.
To make a reservation, go to the Lithuanian Railways website ltglink.lt/en.

Set up an enquiry from Riga to Vilnius.

Click on 1 x Adult (Full price), a panel appears, look for the I have Eurail/Interrail pass toggle at the bottom.

The price will show as €0, it will change to €5 at payment stage.

You print out the reservation or can show it on your phone.

Lithuania

What's covered?

Eurail & Interrail passes give unlimited travel on LG = Lithuanian Railways, ltglink.lt.

Help with train times

See international train times & routes from Vilnius

Using a pass on national trains

Reservations aren't needed, just hop on and show your pass. But prices are incredibly cheap, don't buy a pass for Lithuania before checking normal train fares.

Vilnius ► Poland

Passes cover the Vilnius-Warsaw-Krakow train service, reservation required, €5.
To make a reservation from Vilnius to Warsaw or Krakow in 2nd class:

Go to the Lithuanian Railways website ltglink.lt/en and set up an enquiry from Vilnius to Warszawa or Krakow.

Click on 1 x Adult (Full price), a panel appears, look for the I have Eurail/Interrail pass toggle at the bottom.

The price will show as €0, it will change to €5 at payment stage.

You print out the reservation or can show it on your phone.

The reservation covers both the Lithuanian & Polish trains, the seat number refers to the Polish train, you sit where you like on the Lithuanian train as there are no assigned seats.

You can only reserve in 2nd class this way, as only 2nd class tickets are sold for the international journey.
To make a reservation from Vilnius to Warsaw or Krakow in 1st class, you have to split the booking:

1. Go to the Lithuanian Railways website ltglink.lt/en, set up an enquiry from Vilnius to Mockava, click on 1 x Adult (Full price), a panel appears, look for the I have Eurail/Interrail pass toggle at the bottom. Run the enquiry, select 1st class, the price will show as €0, it will change to €5 at payment stage. You can select a reserved seat in 1st class on this train from a seat map as seats are assigned in 1st class.

2. Now go to Polish Railways www.intercity.pl/en and make a seat reservation from Mockava to Warszawa (Dowolna stacja) following the instructions here. The reservation fee of €3.50 should be shown, continue and buy this reservation.

Vilnius ► Riga

Passes cover the Vilnius-Riga train, seat reservation required, €5 in either class.
To make a reservation, go to the Lithuanian Railways website ltglink.lt/en.

Set up an enquiry from Vilnius to Riga.

Click on 1 x Adult (Full price), a panel appears, look for the I have Eurail/Interrail pass toggle at the bottom.

The price will show as €0, it will change to €5 at payment stage.

You print out the reservation or can show it on your phone.

Luxembourg

What's covered?

Eurail & Interrail passes give unlimited travel on CFL = Luxembourg State Railways, www.cfl.lu.

That includes all domestic local & mainline trains run by CFL and (if you've a global pass) international trains to or from neighbouring countries run by CFL & the partner railways in those countries, including for example the French Railways TGVs to Paris, the regular Intercity trains to Brussels, regional trains to Strasbourg & Germany.

Other pass benefits

A Eurail or Interrail pass gives free travel on buses run by CFL.

Help with train times

See international train times & routes from Luxembourg

Using a pass on national trains

Reservation is neither necessary nor possible on Luxembourg domestic trains, just hop on and sit in any empty seat.

Using a pass on international trains

To Brussels or Amsterdam by intercity (IC) or regional trains: Reservation neither necessary nor possible, hop on, sit in any empty seat and show your pass when asked.
To Paris by TGV: Reservation is compulsory, €10 in either class, or €20 when the €10 reservations sell out. Reserve at Raileurope.com as explained here or using the Interrail/Eurail reservation service. The reservation is emailed to you.
To Trier, Koblenz & Germany by regional train: Reservation is neither necessary nor possible, hop on, sit in any empty seat and show your pass when asked.

Montenegro

What's covered?

Eurail & Interrail passes give unlimited travel on all trains run by ZCG (Railways of Montenegro, www.zcg-prevoz.me).

That includes all domestic local & mainline trains run by ZCG and (if you've a global pass) international trains to or from Serbia run by ZCG & partner SZ (Serbian Railways).

Using a pass on national & international trains

A small supplement must be paid on domestic express trains including the international trains to & from Belgrade, but not on purely local trains.
Bar or Podgorica to Belgrade by sleeper train:
Couchette supplement €6 in a 6-berth or €14 in a 4-berth. Sleeper supplement €15 for a bed in a 3-bed sleeper, €20 for a bed in a 2-bed sleeper, €40 for a single-bed sleeper, all bookable with 2nd class pass. Reservations cannot be made online, make them at the station.

Netherlands

What's covered?

Eurail & Interrail passes give unlimited travel on NS = Nederlandse Spoorwegen = Dutch national railways, www.ns.nl.

That includes all domestic local & mainline trains run by NS and (if you've a global pass) international trains to or from neighbouring countries run by NS & its partner railways, including Eurostar (formerly Thalys) high-speed train to Brussels & Paris, the hourly InterCity trains to Brussels run jointly with SNCB (Belgian Railways), and the DB (German Railways) trains to Germany.
A pass gives free travel on the following private local train operators who now run trains on lines that were part of the NS network: Arriva (Blauwnet, RRReis), Connexxion (Breng), Keolis (Blauwnet, RRReis), Qbuzz (R-Net) and (on cross-border routes to/from Germany) DB Regio & Keolis Deutschland (EuroBahn).
Passes do not cover the RET metro between Hoek van Holland, Schiedam & Rotterdam, so buy a normal metro ticket for around €4.
Tip: Making European seat reservations at stations when in the Netherlands. NS International (Dutch Railways international sales division) charge a fee for making seat reservations at their staffed sales centres at Amsterdam Centraal, Rotterdam, Utrecht, Arnhem etc., in addition to the cost of the reservation: €1.50 per reservation to Belgium or Germany, a whopping €7.50 for reservations to or within all other countries. So make reservations online if you can, or wait until you can get to a ticket office in Germany to make future reservations for other European routes.

Help with train times

For train times within the Netherlands use www.ns.nl.

See international train times & routes from Amsterdam

Using a pass within the Netherlands

Using a railpass within the Netherlands is easy, as reservation is not necessary or even possible on Dutch domestic trains. You can simply hop on any train, find an empty seat and show your pass when asked. That goes for the German InterCity & ICE trains too.
InterCity Direct supplement - yes or no?

If you have a Eurail or Interrail pass, the Eurail/Interrail website states that there's a €2.90 supplement for Dutch domestic journeys made on the Intercity Direct (ICD) trains between Amsterdam/Schiphol & Rotterdam/Breda which use the high-speed line. You can pay this at the station (it's sold by ticket machines or the ticket office) or online at Dutch Railways website www.ns.nl. There's no supplement to pay if you use the slower trains on the classic line through Leiden & Den Haag.

However, this is allegedly incorrect. International tickets are exempt from this supplement and Interrail & Eurail passes are international tickets, so in fact there is no supplement to pay even when making a domestic journey. Even the Eurail/Interrail website accepts that there's no need to pay the ICD supplement when using your pass to travel to or from Belgium, so my advice while any doubt hangs over this issue is to add Amsterdam to Antwerp to your pass (or vice versa) and simply get off (or on) in Rotterdam, then you're 100% exempt either way!
You should avoid making Dutch domestic journeys such as Amsterdam to Rotterdam on the international Eurostar (formerly Thalys) high-speed trains as reservation is required for a hefty fee. Simply use the alternative Dutch InterCity trains instead!

Netherlands ► Great Britain

Eurostar: Amsterdam & Rotterdam to London by Eurostar
Eurail & Interrail passes cover Eurostar to London on payment of a passholder reservation fare of €35 in Standard if you have a 2nd class pass or €43 in Plus if you have a 1st class pass.
You can make Eurostar passholder reservations online as explained here.

Netherlands ► Paris & France

Eurostar (formerly Thalys): Amsterdam & Rotterdam to Paris by Eurostar (formerly Thalys) high-speed train:

Passholder reservation fee Paris-Brussels: €32 in 2nd class, €37 in 1st class.

Passholder places on Eurostar are limited by a quota which can sell out even if the train isn't full, so book ahead.

You can make passholder reservations at Raileurope.com as explained here or b-europe.com as explained here or using the official Eurail/Interrail reservations service.

Regional trains: Netherlands to Brussels by Intercity train then Brussels to Lille by regional train
No reservation is necessary or even possible for cross-border Intercity (IC or ICD) trains between the Netherlands & Brussels, or regional trains from Brussels to Lille. Lille to Paris by TGV is either €10 or €20, see the France section.

Netherlands ► Brussels & Belgium

Eurostar (formerly Thalys): Amsterdam or Rotterdam to Antwerp or Brussels by Eurostar (formerly Thalys) high-speed train:

Passholder reservation fee Paris-Brussels: €22 in 2nd class, €27 in 1st class.

Passholder places are limited by a quota which can sell out even if the train isn't full - so book early! You can avoid the need for a reservation by using the slightly slower Eurocity Direct (ECD) or Eurocity (EC) trains instead.

You can make passholder reservations for Eurostar at Raileurope.com as explained here or b-europe.com as explained here or using the official Eurail/Interrail reservations service.

You can avoid the need for any reservation or fee by using the EuroCity Direct or Eurocity trains.
Eurocity Direct (ECD) trains: Amsterdam Zuid-Rotterdam-Antwerp-Brussels by hourly Eurocity Direct.

No reservation necessary or possible, just hop on, sit in any empty seat and show your pass when asked. Check times at www.b-europe.com.
Eurocity (EC) trains: Rotterdam-Breda-Antwerp-Brussels by (plain) Eurocity train, every hour.

No reservation necessary or possible, just hop on, sit in any empty seat and show your pass when asked. Check times at www.b-europe.com.
Incidentally, there is definitely no need to pay the Dutch €2.90 high-speed Intercity Direct supplement with an Interrail or Eurail pass.

Netherlands ► Berlin, Cologne & Germany

Intercity trains: Amsterdam to Osnabrück, Hanover & Berlin by Intercity (IC) train:

Seat reservation is usually optional, you can just hop on, sit in any empty unreserved seat & show your pass when asked. If you want to reserve seat, you can make a normal seat reservation for around €5 using the German Railways website, as explained here.

Update: In summer from 1 June to 1 September, reservation is compulsory on these cross-border trains. If you find the German Railways website has had seat-only reservations disabled for this period, try using the Austrian Railways website (use Method 2, see the instructions here
ICE trains: Amsterdam or Utrecht to Duisburg, Düsseldorf, Cologne & Frankfurt by ICE train:

Reservation is usually optional, you can normally just hop on, sit in any empty unreserved seat & show your pass when asked. However, these trains often get busy, so making a seat reservation is a good idea. You can make a normal seat reservation for around €5 using the German Railways website, as explained here.

Update: In summer from 1 June to 1 September, reservation is compulsory on these cross-border trains. If you find the German Railways website has had seat-only reservations disabled for this period, try using the Austrian Railways website (use Method 2, see the instructions here
Nightjet sleeper: Amsterdam to Munich by Nightjet sleeper train: See passholder prices.
Passholder reservations for Nightjet sleeper trains can be made online at the ÖBB website using Method 1, see the instructions below.
European Sleeper: Amsterdam or Rotterdam to Berlin & Dresden by European Sleeper overnight train:
Covered by Interrail & Eurail since July 2023. €11 for a seat, €42 for a couchette in 6-berth, €64 for a couchette in 5-berth, €89 for a bed in a 3-bed sleeper, €129 for a bed in a 2-bed sleeper or €159 for a bed in a single sleeper. Same price applies whether your pass is 1st or 2nd class.
You can make reservations at www.europeansleeper.eu by selecting Reservation Only instead of Adult in the Travel group box. booking.

Netherlands ► Austria

Nightjet sleeper: Amsterdam to Vienna by Nightjet sleeper train: See passholder prices.
Passholder reservations for Nightjet sleeper trains can be made online at the ÖBB website using Method 1, see the instructions below.

Netherlands ► Switzerland

Nightjet sleeper: Amsterdam to Basel or Zurich by Nightjet sleeper train: See passholder prices.
Passholder reservations for Nightjet sleeper trains can be made online at the ÖBB website using Method 1, see the instructions below.
You can reserve a seat in the Intercity cars attached to this overnight train for around €5 using the German Railways website, see instructions here. However, a seat is a false economy, always pay for a couchette or sleeper unless they are fully-booked.

ICE: Amsterdam to Basel by ICE:
Seat reservation is normally optional on the direct morning ICE train from Amsterdam to Basel. You can just hop on, sit in any empty unreserved seat & show your pass when asked. However, the train can get busy and reserving a seat is a good idea. You can make a normal seat reservation for around €5 using the German Railways website, as explained here.

Update: In summer from 1 June to 1 September, reservation is compulsory on these cross-border trains. If you find the German Railways website has had seat-only reservations disabled for this period, try using the Austrian Railways website (use Method 2, see the instructions here

Netherlands ► Czech Republic

European Sleeper: Rotterdam or Amsterdam to Prague by European Sleeper overnight train:
Covered by Interrail & Eurail since July 2023. €16 for a seat, €47 for a couchette in 6-berth, €69 for a couchette in 5-berth, €99 for a bed in a 3-bed sleeper, €139 for a bed in a 2-bed sleeper or €169 for a bed in a single sleeper. Same price applies whether your pass is 1st or 2nd class.
You can make reservations at www.europeansleeper.eu by selecting Reservation Only instead of Adult in the Travel group box. booking.

North Macedonia

What's covered?

Eurail & Interrail passes give unlimited travel on MK = Macedonian Railways mzt.mk.

That includes all domestic local & mainline trains run by MK and (if you've a global pass) international trains to or from Greece & Serbia run by MK, OSE (Greece) and SZ (Serbia).
At the time I write this all trains linking Greece, Skopje & Serbia are suspended.

Norway

What's covered?

Eurail & Interrail passes give unlimited travel on trains operated by the 3 national operators www.vy.no, go-aheadnordic.no & www.sj.no.

That includes all domestic local & mainline trains and (if you've a global pass) international trains to or from Sweden run by Vy or SJ (Swedish railways).

The scenic Flåm Railway between Myrdal and Flåm is not included, but you get a 30% discount.

Other pass benefits

50% discount on many regional bus services
30% discount on the Flåm Railway. You cannot buy discounted tickets online, buy at any staffed Norwegian station or via the vy.no call centre. Tip: You can book discounted Flåm Railway tickets using the chat function at entur.no.

Help with train times

For train times within Norway use www.vy.no or www.entur.no.

See international train times & routes from Oslo

Using a pass on Norwegian trains

Reservation is now compulsory on Norwegian long-distance trains with all 3 operators.
2nd class passholders must pay NOK 50 (around €5) on SJ Nord & Go-Ahead, or 70 NOK on Vy (which includes Oslo-Bergen), per seat on each train. You can upgrade to Komfort (1st) class for 200-300 NOK, the upgrade cost varies between operators.
1st class passholders can get seat reservations free of charge for travel in Komfort (1st) class.
Sleeper trains: Around NOK 1200 (€105) for a private sleeper with 1 or 2 beds, per compartment. Book early, sleepers are in high demand.
To make passholder reservations for Norway online:

Go to entur.no. This can reserve seats and even sleepers on Norwegian domestic trains on all 3 major train operators.

Click on the Travellers and add ons panel, reduce the number of adults to 0 and increase the number Interrail/Eurail seat reservations to 1. Remember to say whether your pass is 1st class or 2nd class.
Alternatively, you can also make passholder reservations:

- at a station in Norway with staffed ticket counter (Oslo Sentral, Oslo Airport, Stavanger, Bergen and Trondheim)

- by phone to Vy on +47 61 27 90 88 or +47 61 05 19 10 (no booking fee, the reservation is emailed to you);

- for any Norwegian train, using the chat function on www.entur.no. The reservation is emailed to you.

- on trains run by Vy, by using the chat function at bottom right on the Vy website, www.vy.no. The reservation is emailed to you. If you need to pay for it, they'll email you a payment link.

Using a pass on international trains

Oslo to Stockholm by Intercity train:
Reservation compulsory, €6.60 in 2nd class, €16 in 1st class. You can make passholder reservations online at the Swedish Railways site www.sj.se following the instructions below. You can also make passholder reservations online using the Eurail/Interrail reservations service,
Oslo to Gothenburg by Norwegian train:
Reservation optional, €5.40 if you want a reserved seat. If you have a 1st class pass you can get a reserved seat in NSB Komfort (= 1st class) for free if you make the reservation an any Norwegian station.

Poland

What's covered?

Eurail & Interrail passes give unlimited travel on PKP InterCity = Polish Railways long distance division, www.intercity.pl.

That includes all domestic local & mainline trains run by PKP InterCity and (if you've a global pass) international trains to or from neighbouring countries run by PKP InterCity & its partner railways in those countries.
Passes also give unlimited travel on:

PKP Przewozy Regionalne = Polish Railways regional trains, rozklad-pkp.pl/bin/query.exe/en.

Koleje Dolnośląskie = some local trains around Wroclaw in lower Silesia.

Szybka Kolej Miejska (SKM) = some regional trains around Gdynia.
Interrail passes are not valid on:

Kulturzug regional train Berlin-Wroclaw.

Koleje Mazowieckie = some local trains around Warsaw.

Koleje Śląskie = some local trains in Silesia.

Koleje Wielkopolskie = some local trains around Poznan.

Koleje Malopolska (KML) = some local trains around Krakow & Osweicim

Arriva = a few privatised regional trains around Bydgoszcz/Torun/Gdansk.

International trains to Ukraine and (when running) Belarus & Russia.

Help with train times

For train times within Poland use www.intercity.pl.

See international train times & routes from Warsaw

See international train times & routes from Krakow

Using a pass within Poland

No reservation is necessary or possible for local or regional trains, just get on and show your pass when asked.
EIP (Express InterCity Premium)

These are operated by fast pendolino trains, reservation compulsory, 40 zloty supplement + 3 zloty reservation (= €10).
EIC (Express InterCity), IC (InterCity), TLK (Twoje Linie Kolejowe), EC (EuroCity)

Reservation compulsory, 3 zloty (€0.70)

In fact, a few IC & TLK trains are not reservation compulsory, but it's hard to identify these. As a seat reservation is recommended in any case and only €0.25 booked online or free at the station, it's best to treat all PKP Intercity trains as compulsory reservation. However, if you want to see if a particular train can in fact be used without a reservation, go to portalpasazera.pl/en, run an enquiry, find the train in question, click Connection details, then click the 'i' symbol below the departure station to bring up train facilities. In the list of facilities it will either say obligatory reservation or seat booking. If it says seat booking reservation is optional, not compulsory.
Sleeper trains within Poland

Couchette in 6-berth compartment €14, couchette in 4-berth compartment €16, bed in 3-bed sleeper €18.50, bed in 2-bed sleeper €37, single-bed sleeper €70, all fine with 2nd class pass.
How to make Polish seat reservations online

Option 1: You can reserve seats online for trains within Poland at the PKP Intercity website intercity.pl, following the instructions here.

This is the best way to make Polish domestic train reservations as it's cheapest, there's no added booking fee and you can choose your seat from a seat map on most TLK, IC, EIC & EIP trains.

Booking opens 30 days ahead, you can't book before then! It can't reserve couchettes or sleepers, or reserve seats on international trains, but it will usually happily make passholder reservations for Polish domestic journeys.

Made online, a seat reservation costs 3 zloty (€0.70) on a EIC, IC or TLK train or 43 zlotys (€10) on an EIP train, with no booking fee.

If you have any problems with this method, use option 2:

Option 2: You can also reserve seats online for trains within Poland at the Czech Railways website www.cd.cz, at least on a good day, for €3 per seat, €13 for a premium EIP train. Remember that Polish domestic reservations only open 30 days ahead.

Go to www.cd.cz and run an enquiry as if buying a ticket, locate the train you want in the search results, click on the down arrow in the green Purchase a ticket button and select Purchase reservations only.

Incidentally, cd.cz won't specifically mention Interrail or Eurail, but it doesn't need to, as all you need as a passholder for Polish trains is a normal seat reservation, the same reservation that any ticket-holder is entitled to buy. It's not a special one specifically for passholders!
How to make sleeper reservations online

Polish domestic sleeper reservations can't be made at the Polish Railways website, but (surprisingly) can be made at the Czech Railways website www.cd.cz, at least on a good day. Go to www.cd.cz and run an enquiry as if buying a ticket, locate the train you want in the search results, click on the down arrow in the green Purchase a ticket button and select Purchase reservations only. Change seat to sleeper, and if you're lucky it'll book it. Remember that Polish domestic reservations only open 30 days ahead!

Poland ► Berlin & Germany

EuroCity trains: Warsaw, Poznan, Gdynia, Gdansk, Krakow or Wroclaw to Berlin by EuroCity train

Reservation is compulsory, €5.20 in 2nd class, €6.50 in 1st class if you use DB or just €4 if you reserve using PKP.

You can make a seat reservation using the DB (German Railways) site as explained here and print it out or show it on your phone.

Or your can use the PKP Intercity (Polish Railways) website as explained here, also printing it out or showing it on your phone

Poland ► Vienna & Austria

EuroCity trains: Warsaw or Krakow to Vienna by EuroCity train

Reservation is compulsory, seat reservation fee €3. This is just a normal seat reservation like any other passenger with a pre-existing ticket would make, you can make a reservation online at the ÖBB website for €3 using Method 2, see the instructions here.
Sleeper train: Warsaw or Krakow to Vienna by EuroNight sleeper train:
€29 for a couchette in 6-berth, €39 for a couchette in 4-berth, €44 for a bed in a 3-bed sleeper, €59 for a bed in a 2-bed sleeper, €119 for a bed in a single-bed sleeper, €79 for a bed in a 2-bed sleeper with shower & toilet, €139 for a bed in a single-bed sleeper with shower & toilet (all fine with 2nd class pass).

You can make a passholder reservation online at the ÖBB website using Method 1, see the instructions here.

Poland ► Prague & Czechia

EuroCity trains: Warsaw or Krakow to Prague by EuroCity train

Reservation is compulsory, but you only need a normal seat reservation for around €3.
You can reserve a seat online at the CD (Czech Railways) website, see the instructions here.
Sleeper train: Warsaw or Krakow to Prague by EuroNight sleeper train
€13.40 per person in 6-bunk couchette, €?? in 4-bunk couchette, bed in 3-bed sleeper €20, bed in 2-bed sleeper €30, bed in single-bed sleeper €70, bed in 2-bed sleeper with shower & toilet €??, bed in single-bed sleeper with shower & toilet €80.

Passholder reservations for the Warsaw/Krakow to Prague sleeper train can be made online at the Czech Railways website www.cd.cz, with no added booking fee. Before running the enquiry, click where it says 1 x Adult 26-64 No discount card then click on No discount card , click Interrail and Eurail Pass then select the one you have. You print your own ticket or can show it on your phone.

Leo Express: Krakow to Prague by private operator Leo Express, see timetable here
2nd class passes entitle you to free travel in economy class, 1st class passes in standard plus or business class. Reservation is required, but it's free of charge, you can make passholder reservations in person at their Prague or Ostrava offices or online at leoexpress.com following the advice here. Upgrade to Premium class is not possible.

Poland ► Bratislava or Budapest

EuroCity trains: Warsaw or Krakow to Bratislava or Budapest by EuroCity train

Reservation is compulsory, but you only need a normal seat reservation for around €3.
You can (surprisingly, perhaps) make a seat reservation using the CD (Czech Railways) website, see the instructions here.
Or you can make a seat reservation using the ÖBB (Austrian Railways) website using Method 2, see the instructions here.
Sleeper train: Warsaw or Krakow to Bratislava or Budapest by EuroNight sleeper train:
€17 for a couchette in a 6-bunk couchette, €32 for a bed in a 3-berth sleeper, €44 for a bed in a 2-bed sleeper, €83 in a single-bed sleeper, €55 for a bed in a 2-bed sleeper with shower & toilet, €93 in a single-bed sleeper with shower & toilet, all bookable with a 2nd class pass. This cannot be booked online, ask www.polrail.com to do it for you with ticket collection in Warsaw or Krakow, or use the Eurail/Interrail reservations service (a hard copy ticket must be posted to you at extra cost).

Poland ► Vilnius

Passes cover the Warsaw-Vilnius train service, reservation required, €5.
To make a reservation from Krakow or Warsaw to Vilnius in 2nd class:

Go to the Lithuanian Railways website ltglink.lt/en and set up an enquiry from Krakow or Warszawa to Vilnius.

Click on 1 x Adult (Full price), a panel appears, look for the I have Eurail/Interrail pass toggle at the bottom.

The price will show as €0, it will change to €5 at payment stage.

The reservation covers both the Polish & Lithuanian trains, the seat number refers to the Polish train, you sit where you like on the Lithuanian train as there are no assigned seats.

You print out the reservation or can show it on your phone.

You can only reserve in 2nd class this way, as only 2nd class tickets are sold for the international journey.
To make a reservation in 1st class, you have to split the booking:

1. Go to Polish Railways www.intercity.pl/en. Make a seat reservation from Warszawa (Dowolna stacja) to Mockava following the instructions here. A reservation fee of €3.50 should be shown, continue and buy this reservation.

2. Now go to the Lithuanian Railways website ltglink.lt/en, set up an enquiry from Mockava to Vilnius, click on 1 x Adult (Full price), a panel appears, look for the I have Eurail/Interrail pass toggle at the bottom. Run the enquiry, the price will show as €0, it will change to €5 at payment stage. You can select a reserved seat in 1st class on this train from a seat map as seats are assigned in 1st class.

Portugal

What's covered?

Eurail & Interrail passes give unlimited travel on CP = Portuguese national railways, www.cp.pt.

That includes all domestic local & mainline trains run by CP and (if you've a global pass) international trains to or from Spain and the French border run by CP & its partner Renfe (Spanish railways).

Help with train times

For train times within Portugal see www.cp.pt.

See international train times & routes from Lisbon

See international train times & routes from Porto

See international train times & routes from Faro & the Algarve

Using a pass on Portuguese trains

Seat reservation is neither necessary nor possible on local, regional or InterRegional trains. Just get on the train, sit where you like, and show your pass when asked.
InterCity trains, for example Lisbon-Faro: Reservation required, €5.

Tip: If you haven't time to make a reservation at the ticket office, try approaching the conductor and asking if they can help with a reservation.

Alfa Pendular fast tilting trains, for example Lisbon-Porto: Reservation required, €5.
Reservations for Portuguese trains can't be made anywhere outside Portugal, just make them at any main station when you get there, there are almost always places available.

Using a pass on international trains

Lisbon to Madrid: See here for Lisbon-Madrid timetable & journey details, then see here for reservation requirements & how to book.
Porto-Vigo by express regional train: You can ask for a seat reservation at the station before boarding free of charge, or you can pay €1.50 to reserve online at www.happyrail.com (tip: It initially says it will cost €8, but after entering passenger details this will change to €1.50).
Tip: Lisbon Santa Apolonia and Porto Campanhã stations are equipped with Renfe's (Spanish Railways) ticketing system so can sell reservations on Spanish trains as well as Portuguese.

Romania

What's covered?

Eurail & Interrail passes give unlimited travel on CFR = Romanian National Railways, www.cfrcalatori.ro.

That includes all domestic local & mainline trains run by CFR and (if you've a global pass) international trains to or from neighbouring countries jointly run by CFR & the national railways in those countries.

Help with train times

See international train times & routes from Bucharest

Using a pass on Romanian trains

InterCity (IC) & InterRegio (IR) trains: Seat reservation is compulsory, costing around €1. This is just a normal seat reservation as for any ticket holder. Make reservations at the station, reservations cannot be made online.

Romania ► Austria

Bucharest, Brasov or Sighisoara to Vienna by sleeper train Dacia Express:
Reservation required, couchette in 6-bunk compartment €13.40, couchette in 4-bunk couchette €20, berth in 3-berth sleeper €28, berth in 2-berth sleeper €42. Bed in single-bed sleeper (requires 1st class pass) €98.
You can make passholder reservations for sleepers & couchettes on the Dacia Express at the ÖBB (Austrian Railways) website using Method 1, see the instructions below and can print out the reservation.

Romania ► Hungary

Bucharest or Brasov to Budapest by daytime train:
Seat reservation is compulsory, it costs around €3, this is a normal seat reservation as for any ticket holder. Reservations cannot be made online, make them at the international ticket office in Bucharest or another station.
Bucharest or Brasov to Budapest by sleeper train:
Reservation required, couchette in 6-bunk compartment €13.40, couchette in 4-bunk couchette €20, berth in 3-berth sleeper €28, berth in 2-berth sleeper €42. Bed in single-bed sleeper (requires a 1st class pass) €98.
Option 1, book using the Interrail/Eurail reservation service as explained here, the reservation is emailed to you and you print it out.
Option 2, you can also make a Bucharest-Budapest sleeper or couchette reservation on the Dacia Express (but not other trains) at the ÖBB (Austrian Railways) website using Method 1, see the instructions below. You print out the reservation.
Option 3, you can also make reservations on all these sleeper trains using the Hungarian Railways website as explained below. This way you pay no booking fee. You print out the reservation.

Romania ► Bulgaria

Bucharest to Ruse & Sofia: Reservation required. Reservations cannot be made online, make them at the international ticket office in Bucharest or another station.

Romania ► Turkey

Bucharest to Istanbul by sleeper train (runs direct in summer only):
€14 supplement for a couchette in 4-berth compartment. Reservations cannot be made online, reserve at the station or as shown here.

Serbia

What's covered?

Eurail & Interrail passes give unlimited travel on ZS = Serbian Railways, www.serbianrailways.com.

That includes all domestic local & mainline trains run by ZS and (if you've a global pass) international trains to or from neighbouring countries run jointly by ZS & the national railways in those countries.

Help with train times

See international train times & routes from Belgrade

Using a pass on Serbian trains

Reservation is optional on express trains, for €0.90.

Using a pass on international trains

Reservation is optional on the Belgrade-Zagreb-Ljubljana train (if & when running), you can just get on and show your pass when asked. If you want a reserved seat you can do this at the station for a few euros, this is just a normal seat reservation as for any ticket holder.
Belgrade to Podgorica or Bar by sleeper train Lovcen:

Couchette supplement €6 in a 6-berth or €14 in a 4-berth. Sleeper supplement €15 for a bed in a 3-bed sleeper, €20 for a bed in a 2-bed sleeper, €40 for a single-bed sleeper, all bookable with 2nd class pass. Reservations cannot be made online, make them at the station.

Slovakia

What's covered?

Eurail & Interrail passes give unlimited travel on ZSSK = Slovak Railways, www.zssk.sk.

That includes all domestic local & mainline trains run by ZSSK and (if you've a global pass) international trains to or from neighbouring countries run jointly by ZSSK & the national railways in those countries.
Passes now cover private operator Regiojet too.

Help with train times

See international train times & routes from Bratislava

Using a pass within Slovakia

Seat reservation is compulsory on all InterCity & EuroCity trains, the cost varies between €1-€10 in 2nd class or €7-€16 in 1st class depending on distance. It's just a normal seat reservation, as for any other ticket holder.
You can make reservations for €2 in either class at the Slovakian Railways website predaj.zssk.sk/search
Click Menu and look for the Switch to English language link.
Run an enquiry and find the train you want. Click on the shopping trolley icon then Purchase the ticket. Then click on No Discount, select International ticket/Rail Pass from the list and click Continue. Click Seat ticket to see the reservation options, pick one and make the reservation. At the next stage you'll usually get to choose an exact seat from a seat map. You get a barcode to print or show on your phone.

Using a pass on international trains

Bratislava to Budapest by EuroCity or Intercity train:
Seat reservation is optional, but a very good idea as these trains can get busy, especially in summer. It's just a normal seat reservation as for any ticket holder.
You can reserve a seat for €3 in either class using the CD (Czech Railways) website, see the instructions here.
Or you can reserve a seat for €2 in either class at the Slovakian Railways website predaj.zssk.sk/search, in the same way as for within Slovakia.

Bratislava to Prague by EuroCity or Intercity train:
Seat reservation is optional, but a very good idea as these trains can get busy, especially in summer. It's just a normal seat reservation as for any ticket holder. Book at the station, there are almost always places even on the day.
You can reserve a seat for €3 in either class using the CD (Czech Railways) website, see the instructions here.
Or you can reserve a seat for €2 in either class at the Slovakian Railways website predaj.zssk.sk/search, in the same way as for within Slovakia.
SuperCity tilting trains from Košice & Poprad Tatry to Ostrava & Prague:
Seat reservation is compulsory on SuperCity tilting trains from Košice & Poprad Tatry to Ostrava & Prague, €7, a normal seat reservation as for any ticket holder.
You can reserve a seat using the CD (Czech Railways) website, see the instructions here.
Or you can reserve a seat at the Slovakian Railways website predaj.zssk.sk/search, in the same way as for within Slovakia.

Bratislava to Prague by Regiojet train:
Reservation required, €1.3 in Low Cost, €2 in Standard, €2.8 in Relax or (with a 1st class pass) €1.3 in Business.
Regiojet passholder reservations can be made online at www.regiojet.com: Use the journey planner as if buying a normal ticket. When prices appear, look for the Only seat reservations toggle and use it. Select the train you want, then under Type of ticket purchased select Interrail & Eurail. You print out your reservation or can show it in the Regiojet app. Or book at the Regiojet ticket window at Bratislava Hlavna.

Bratislava to Krakow or Warsaw by EuroNight sleeper train:
€17 for a couchette in a 6-bunk couchette, €32 for a bed in a 3-berth sleeper, €44 for a bed in a 2-bed sleeper, €83 in a single-bed sleeper, €55 for a bed in a 2-bed sleeper with shower & toilet, €93 in a single-bed sleeper with shower & toilet, all bookable with a 2nd class pass.
You can reserve a seat, couchette or sleeper using the CD (Czech Railways) website, see the instructions here. .
Bratislava to Berlin by EuroNight sleeper train:
Couchette in 6-berth €44, couchette in 4-berth €54, bed in 3-bed sleeper €69, in 2-bed €94, in single-bed €169, all accommodation types can be booked with a 2nd class pass.

Passholder reservations for sleepers or couchettes can be made online at the ÖBB website using Method 1, see the instructions below.
Bratislava to Dresden or Berlin by EuroCity train Hungaria:
Reservation is optional on this train, you can just hop on, sit in any empty unreserved seat & show your pass when asked. However, it can get very busy in summer and on Fridays & Sundays all year so I'd strongly recommend reserving a seat.

You can make a normal seat reservation for €3 to €5 using either the German Railways website as explained here or the Czech Railways website as explained here.
Update: In summer from 1 June to 1 September, reservation is compulsory on these cross-border trains.

Slovenia

What's covered?

Eurail & Interrail passes give unlimited travel on SZ = Slovenian railways, potniski.sz.si.

That includes all domestic local & mainline trains run by SZ and (if you've a global pass) international trains to or from neighbouring countries run by SZ & the national railways in those countries.

Help with train times

See international train times & routes from Ljubljana

Using a pass on Slovenian trains

Seat reservation is compulsory on all ICS trains, costing between €2-€4 depending on distance.

Using a pass on international trains

Ljubljana or Lesce-Bled to Salzburg or Munich by EuroCity train:
Reservation optional, you can just get on and show your pass when asked. If you want a reserved seat you can make a normal seat reservation for €5.20 in 2nd class or €6.50 on 1st class at the German Railways website as shown here. It's just an ordinary seat reservation, so you use the Book seat only link under the red search button to run the enquiry.
Ljubljana to Vienna by EuroCity train:
Reservation optional, you can just get on and show your pass when asked. If you want a reserved seat you can make a normal seat reservation for around €3 at the Austrian Railways website using Method 2, see the instructions below.

Ljubljana to Budapest by train:
Seat reservation is compulsory, €3 per seat. It's just a normal seat reservation which can be made using using the CD (Czech Railways) website, see the instructions here.
Ljubljana or Lesce-Bled to Zagreb:

Reservation optional. You can reserve a seat for €3 at least on some departures, using the Austrian ÖBB website using Method 2, as shown here.
Ljubljana or Lesce-Bled to Munich, Stuttgart or Zurich by sleeper train:
Couchette in 6-berth €29.90, couchette in 4-berth €34.90, bed in 3-bed sleeper €64.90, in 2-bed €109.90, in single-bed €234.90.

Prices vary slightly according to demand. All types of couchette or sleeper can be booked with any class of pass.

Passholder reservations for sleepers or couchettes can be made online at the ÖBB website using Method 1, see the instructions below.
Ljubljana to Belgrade:

Reservation optional, you can just get on and show your pass when asked.
Ljubljana to Trieste by twice-daily regional train

Reservation neither necessary nor possible, just hop on, sit where you like, show your pass when asked.
Ljubljana to Trieste by once-daily EuroCity train:

There is a small passholder surcharge for the part within Italy, €2.60, but seat reservation is optional.
You can board the train without a reservation, sit in any empty unreserved seat and pay the surcharge on board when the conductor comes round, or you can make a seat reservation & pay the surcharge at the Austrian Railways website using Method 1, see the instructions below.

Spain

What's covered?

Eurail & Interrail passes give unlimited travel on Renfe = Spanish national railways, www.renfe.com.

That includes all domestic high-speed & long-distance trains (AVE, Euromed, Alvia, Intercity), medium-distance (Media Distancia), regional and suburban (cercanias/rodalies) trains run by Renfe.

A global pass also covers international trains to/from France & Portugal run by Renfe, SNCF (French Railways) and CP (Portuguese Railways).
It also includes the former FEVE narrow-gauge local trains in northern Spain around Bilbao, Gijón, León & Santander, as these are now part of Renfe, timetables & routes are on www.renfe.com for longer-distance regional services and on the Cercanias (suburban) pages for each city.
From 1 April 2025 Interrail & Eurail passes also cover Iryo trains which compete with Renfe on key high-speed routes.
There's a 30% discount on AML ferries between Algeciras & Tanger Med (Morocco), see aml.ma. However, AML don't offer the discount on the more convenient ferry from Tarifa to Tangier Town.

What's not covered

Interrail & Eurail passes do not cover the lo-cost Avlo trains or Ouigo trains which compete with Renfe.
Until 31 March 2025 Interrail & Eurail passes don't cover Iryo trains which compete with Renfe on key high-speed routes.
Interrail & Eurail passes do not cover Euskotren (www.euskotren.eus) narrow gauge trains Hendaye-San Sebastian-Bilbao.
There is no longer any pass discount on ferries to Ibiza or Majorca.

Help with train times

For train times within Spain use www.renfe.com or www.thetrainline.com.

See international train times & routes from Barcelona

See international train times & routes from San Sebastian

See international train times & routes from Madrid, Valencia, Alicante, Granada, Seville, Malaga

Using a pass within Spain

Reality check: Almost all Spanish trains require a reservation

Spain is not a pass-friendly country. All long & medium-distance trains and even many short distance ones require a reservation.

It's safest to assume that the only Spanish trains which don't require a seat reservation are suburban trains (cercanias/rodalies) in and around the big cities, including the rural Barcelona-Latour de Carol & Barcelona-Portbou-Cerbère routes across the French border.
Renfe's own website renfe.com does NOT sell passholder reservations. But there are 3 websites that can, read on.

What do reservations cost?

AVE high-speed trains

AVEs are Renfe's premier trains. Routes include Madrid to Barcelona, Alicante, Valencia, Seville, Cordoba, Malaga. Barcelona to Madrid, Granada, Malaga, Cordoba, Seville:

€10 in 2nd class (estandar) or €13 in 1st class (confort).

There's also a €23.50 premium 1st class reservation fee which gives you a 1st class seat with Sala Club lounge access and an at-seat meal (or snack, on some departures) with wine included, but this is only available at stations or from Raileurope.com, not from all retailers. There is no meal or Sala Club access with a regular 1st class confort reservation.
Euromed

Euromeds operate on the Barcelona-Valencia-Alicante corridor:

€6.60 in 2nd class (estandar), €10 in 1st class (confort).

There is also a €23.50 premium 1st class reservation fee which gives you a 1st class seat with Sala Club lounge access and an at-seat meal (or snack, on some departures) with wine included, but this is only available at stations directly from Renfe. There is no meal or Sala Club access with the normal 1st class fee.
Alvia & Intercity

Alvias operate on routes such as Madrid-Cadiz, San Sebastian-Barcelona, Bilbao-Barcelona, Madrid-Vigo, Madrid-Algeciras, Madrid-Badajoz:

€6.60 in 2nd class (estandar) or €10 in 1st class (confort).
Avant

High-speed trains for short distances: €4 per seat.
Media Distancia

Even many shorter-distance regional trains in Spain require a seat reservation, including Media Distancia (MD) trains: €4 per seat.
Cercanias/Rodalies

Suburban trains around big cities, including the rural routes Barcelona-Latour de Carol and Barcelona-Portbou-Cerbère: No reservation necessary or possible, get on, sit anywhere, show your pass when asked.
Iryo - competing high-speed operator
Iryo is a high-speed operator competing with Renfe's AVE on major routes, including Madrid to Barcelona, Alicante, Valencia, Seville, Cordoba, Malaga and Barcelona-Seville & Barcelona-Malaga.

Singular (2nd) class €10. Singular Only You (1st) class: €13.

How to make reservations for Spain

Option 1, use Raileurope.com as explained here

You can make reservations for most (but not necessarily all) AVE, Euromed, Alvia & Intercity trains using Raileurope.com as explained here.

Raileurope offers two key advantages: (a) No booking fee, you just pay for the reservation itself, options 2 & 3 add a small fee. (b) As well as regular Elige Interrail Standard (2nd class) and Elige Interrail Comfort (1st class) reservations, if you have a 1st class pass you can choose the higher-priced Premium Interrail Comfort reservation on AVE trains, this gets you Sala Club lounge access at major stations and included drinks/snacks/meal on the train - recommended!

Booking for Spanish trains opens anything from 15 days to 11 months ahead, depending what side of bed Renfe's management got out of that morning. On routes with competition such as Madrid-Barcelona & Madrid-Seville, booking may open up to 11 months ahead, but in 2023, Madrid-San Sebastian trains for a block of dates from 22 July onwards only finally opened for sale on 7 July. That's Renfe for you!
Option 2, use the Interrail/Eurail reservation service

You can make Renfe & Iryo reservations online using the Interrail/Eurail reservations service.

Until July 2023 it was impossible to make Spanish passholder reservations online anywhere, but the official Interrail/Eurail reservations service now offers passholder reservations on most AVEs and some Alvia/Intercity/Euromed trains, having finally persuaded Renfe to let them.

At the time I write this, you can only make regular 1st & 2nd class reservations this way, not the AVE Premium reservation with lounge access and food & drink included.

See whether it works for your specific trains. If it won't, try options 1 & 3, if they too fail and you can't afford to take pot luck at the station, consider buying point-to-point tickets instead using www.renfe.com (in €, fiddly) or www.thetrainline.com (easy to use, in €, £ or $, small booking fee). Point-to-point prices include the necessary reservation and you get to select your seat from a seat map.
Option 3, use www.happyrail.com

You can make many Spanish reservations online at www.happyrail.com, a reliable Dutch agency. There's a 3.5% booking fee. Simply change Tickets to Reservations. This can work even in cases where option 2 fails.

Option 4, make reservations at the ticket office at any Renfe station

At big stations there's a numbered queuing system, take a number from the pink machine inside the ticket office entrance and wait till your number is called on the video screen.

I recommend writing down what you want and showing it to the clerk: From/to, date, time, class, number of passengers, seating preferences.

Be warned, at busy stations such as Madrid Atocha, Madrid Chamartin or Barcelona Sants it can take over an hour to get served or in summer as much as two hours. Try to make reservations at smaller stations, not Madrid or Barcelona. You can book multiple journeys at the same time at any Renfe station, of course. In Barcelona, try going to the relatively quiet Barcelona Franca, it can be quicker than queuing at Barcelona Sants.

If your time is valuable, consider buying normal point-to-point tickets on your phone rather than wasting precious hours of your time in the city.

Remember that Spanish long-distance trains aren't as frequent as in other countries and can get full, especially on Friday & Sunday afternoons, in summer and at Easter or Christmas. So book as soon as you can and be prepared to be flexible.

Spain ► France

French TGV trains to southern France & Paris
Barcelona to Narbonne, Perpignan, Montpellier, Nimes, Valence & Paris by French Railways (SNCF) TGV:
Reservation compulsory, passholder fee a hefty €35 in 1st or 2nd class.
Pass holder places are controlled by quota, so places can sell out before the train itself is full.
You can make passholder reservations online at Raileurope.com as explained here or using the Eurail/Interrail reservations service.
Or you can make reservations at www.happyrail.com, a reliable Dutch agency, with a 3.5% booking fee. Change Tickets to Reservations.
It's e-ticketed, the reservation is emailed to you and can be printed or shown on your phone.
Spanish AVE trains to Perpignan, Nîmes, Montpellier, Lyon & Marseille: No longer a problem
Every morning, a Spanish AVE S100 links Barcelona to Narbonne, Perpignan, Montpellier, Nimes & Lyon.
Every afternoon, a Spanish AVE S100 links Madrid & Barcelona to Narbonne, Perpignan, Montpellier, Nimes, Avignon & Marseille.
Operated by Renfe (Spanish Railways), they enter France on an open-access basis in competition with SNCF (French Railways).

The reservation fee is €10 in 2nd class, €13 in 1st class. A lot cheaper than SNCF's TGVs!
You can make passholder reservations on these trains using Raileurope.com as explained here, with no added booking fee.

Or you can use the Eurail/Interrail reservations service or use www.happyrail.com, a reliable Dutch agency, with a 3.5% booking fee (change Tickets to Reservations).

An e-ticket is emailed to you.
How to avoid expensive reservation fees:
Option 1, Barcelona to Latour de Carol to Toulouse: There are no fees to pay or reservations required on the local suburban trains from Barcelona through the Pyrenees to Latour de Carol and on the TER regional trains from Latour de Carol to Toulouse, see here for details.
Option 2, Barcelona - Cerbère- Perpignan: Take a Spanish regional train from Barcelona to Cerbère then a French TER regional train from Cerbère to Perpignan, no reservation necessary for either train. Then take a TGV from Perpignan to Paris or wherever, €10 reservation fee booked in advance or €20 fee when the €10 fees sell out, easily bookable online without any booking fee as shown here. The easiest way to find times is to use the Barcelona area regional trains website rodalies.gencat.cat/en/horaris to look up trains from Barcelona to Cerbère. Then use int.bahn.de to look up trains from Cerbère to Paris/Lyon/Montpellier/Avignon/wherever.
Option 3, via San Sebastian at the northern end of the Pyrenees: Take a Spanish train from Madrid, Barcelona or wherever to San Sebastian at the northern end of the Pyrenees, reservation fee €10, make this at the station, there's no quota so only sells out at the busiest times. You can check times at www.raileurope.com. Then take the little Euskotren metro from San Sebastian Amara station to Hendaye, which is not covered by Interrail or Eurail, but the fare is only €2.50 or so, buy at the station, it runs every 30 minutes and takes 37 minutes. Then take a TGV from Hendaye to Bordeaux or Paris, €10 fee in advance or €20 fee when the €10 fees sell out, easily bookable online as shown here. You'll also find fee-free TER trains from Hendaye to Biarritz and Bordeaux.

Spain ► Portugal

Madrid to Lisbon by day trains: See here for Madrid-Lisbon timetable & journey details and here for reservation requirements & how to book.
Vigo to Porto by regional express train: You can ask for a seat reservation at the station before boarding free of charge, or you can pay €1.50 to reserve online at www.happyrail.com (tip: It initially says it will cost €8, but after entering passenger details this will change to €1.50).

Sweden

What's covered?

Eurail & Interrail passes give unlimited travel on SJ = Swedish national railways www.sj.se, which runs most Swedish mainline trains.

That includes all domestic local & mainline trains run by SJ and (if you've a global pass) international trains to or from Denmark & Norway run by SJ & its partner railways in those countries.
Passes also give unlimited travel on:

Öresundståg = operator of local trains linking Copenhagen, Malmo, Gothenburg.

Arlanda Express airport rail link.

Inlandsbanen private local railway up the inner spine of Sweden.

Snälltåget = private operator running Malmo-Stockholm & Malmo-Berlin, www.snalltaget.se.

Local operators Arriva, Krösatåg, Norrtåg, Skånetrafiken, Värmlandstrafik, Västtrafik, Mälartåg.

Tallink-Silja Line ferries Stockholm-Turku (for train to Helsinki). Cabin berths extra.

Free travel on Net Matkat bus service Kemi/Tornio-Haparanda (across the top from Sweden into Finland).
Passes do not cover private operators MTRX or Flixtrain running Stockholm-Gothenburg trains in competition with SJ.

Other pass benefits

50% discount on Viking Line ferries Stockholm-Helsinki and Stockholm-Turku.
30% discount on Stena Line ferries (including Gothenburg-Frederikshavn in Denmark).
Special fares on Tallink-Silja Line ferries Stockholm-Riga, Stockholm-Tallinn.

Help with train times

For train times within Sweden use www.sj.se.

See international train times & routes from Stockholm

Using a pass within Sweden

X2000 trains, for example, Stockholm-Gothenburg or Stockholm-Malmö by X2000 train.

Reservation compulsory, fee €7 in 2nd class or €17 in 1st class (includes a light meal in 1st class).

You can make seat reservations on SJ trains at www.sj.se following the instructions below.

Sj.se occasionally struggles with overseas credit cards. If you have any problems using it you can also make passholder reservations for Sweden at www.trainplanet.com by first switching it to Interrail mode using the toggle under the journey planner. Trainplanet charges a small booking fee.
Intercity trains: Reservation compulsory, 35 SEK in either class.
Sleeper trains within Sweden:
Seat €3, couchette in 6-bunk compartment €20, bed in 3-bed sleeper with washbasin €40, bed in 2-bed sleeper with toilet & shower €50, single-bed sleeper with toilet & shower €75.
You can make couchette and sleeper reservations on SJ trains at www.sj.se following the instructions below.
Snälltåget (private competitor to SJ) Malmö-Stockholm: Reservation required, €5 in 2nd class, €15 in 1st class.
You can make a passholder reservation online at www.snalltaget.se/en, simply tick the I have an Interrail or Eurail Pass box in the Travellers panel.

Using a pass on international trains

Stockholm to Copenhagen by X2000
Reservation compulsory, €6.60 in 2nd class, €16 in 1st class.
You can make Stockholm-Copenhagen passholder reservations online with no booking fee at www.sj.se following the instructions below.
You can also make them at the Eurail/Interrail reservations service, the reservation is e-ticketed and emailed to you in minutes.
Snälltåget run Stockholm to Copenhagen once or twice a day through the summer in competition with SJ.
Reservation required, €5 in 2nd class, €15 in 1st class.
You can make a passholder reservation online at www.snalltaget.se/en, simply tick the I have an Interrail or Eurail Pass box in the Travellers panel.
Stockholm to Oslo by Intercity train:
Reservation compulsory, €6.60 in 2nd class, €16 in 1st class.
You can make Stockholm-Oslo passholder reservations online using the Eurail/Interrail reservations service, the reservation is e-ticketed and emailed to you in minutes. You can also make them with no added booking fee at www.sj.se following the instructions below (no booking fee) or at www.trainplanet.com by first switching it to Interrail mode using the toggle under the journey planner (small booking fee).
Gothenburg to Oslo:
Reservation optional. You can just get on and sit in any empty unreserved seat.
Öresund trains: Gothenburg & Malmö to Copenhagen by Öresund train:
Reservation unnecessary, just get on, sit where you like and show your pass when asked.
SJ sleeper train: Stockholm to Hamburg or Berlin by SJ EuroNight sleeper train:
Reservation required. You can book passholder places in couchettes or sleepers at the Swedish Railways website www.sj.se by adding an Interrail/Eurail discount to each passenger, see the instructions below.
If you have any problems you can also make passholder reservations at www.trainplanet.com by first switching it to Interrail mode using the toggle under the journey planner.
Snälltåget sleeper train: Stockholm or Malmö to Hamburg or Berlin by Snälltåget overnight train:
Reservation required, €19 in a seat, €39 with couchette.
You can make a passholder reservation online at www.snalltaget.se/en, simply tick the I have an Interrail or Eurail Pass box in the Travellers panel.
Sweden to Germany by day trains changing at Copenhagen:
See the Germany to Denmark & Denmark to Sweden sections.

Switzerland

What's covered?

Eurail & Interrail passes give unlimited travel on Swiss Federal Railways (SBB, www.sbb.ch) which runs most inter-city trains and many regional ones.

That includes all domestic trains run by SBB and (if you've a global pass) international trains to or from neighbouring countries run jointly by SBB & other national railways.

Tip: If you are also visiting Paris or Italy, it's often cheaper to combine a one-country Swiss pass with a cheap advance-purchase ticket between Paris & Switzerland or Switzerland & Italy, rather than buying a global pass and paying reservation fees for the international trains. So do the maths!
The Glacier Express route from Zermatt to St Moritz is part run by the Matterhorn Gotthard Bahn (MGB) and part by the Rhätische Bahn (RhB) both now covered by Eurail & Interrail passes. How to make an online reservation for the Glacier Express if you have a railpass.
The Bernina Express route Chur-St Moritz-Tirano is entirely run by RhB, so covered by Eurail & Interrail. How to make an online reservation for the Bernina Express if you have a railpass.
The Golden Pass route Montreux - Interlaken - Lucerne is also fully covered by Interrail & Eurail passes, as is the Mont Blanc Express between Martigny, Chamonix-Mont Blanc & St Gervais in France as it's run by TMR & SNCF.
Interrail & Eurail passes give free travel on these private railways:

AB Appenzeller Bahnen (25% discount on Ligerz - Tessenberg, free on all other routes)

ASM Aare Seeland Mobil

BLS Bern-Lötschberg-Simplon (which runs the main Bern-Interlaken-Brig line)

BOB Berner Oberland Bahnen (incl. Interlaken to Grindelwald, Lauterbrunnen, Mürren, Wengen) Added in 2024

CJ Chemins de fer du Jura

FART Ferrovie Autolinee Regionall Ticinesi (the Centovalli railway)

FB Forchbahn

LEB Lausanne - Echallens - Bercher

MBC Bière - Apples - Morges

MGB Matterhorn Gotthard Bahn - new from 2017!

MOB Montreux Oberland Bernois

MVR Transports Montreux - Vevey - Riviera

NStCM Chemin de Fer Nyon - St-Cergue - Morez

RA RegionAlps Martigny - Orsières / Le Chàble

RBS Regionalverkehr Bern Solothurn

RhB Rhätische Bahn (Disentis-Chur-St Moritz-Tirano)

SOB Sudostbahn

SOB-bt Bodensee Toggenburg Bahn

SSIF Societa Subalpina di Imprese Ferroviarie

THURBO Mittelthrugau Bahn

TILO - a consortium of SBB & Trenord running Locarno-Lugano-Milan.

TMR Martigny - Châtelard (- Chamonix Mont Blanc)

TPC Transports publics du Chablais
TPF Transports publics Fribourgeois

TRAVYS SA

TRN Transports régionaux Neuchâtelois

Voralpen Express

WB Waldenburgerbahn
WSB Wynental & Suhrentalbahn

ZB Centralbahn

See full list here.
Interrail holders get 25% or 50% discount on these other private train & bus services:

BB Kehrsiten - Bürgenstock

BET Bergbahnen Engelberg to Titlis 25% off

JB Jungfraubahn 25% off - see the train up the Jungfrau page.
LAF Luftseilbahn Adliswil - Felsenegg
PB Pilatusbahn (Alpnachstad-Pilatus Kulm/Kriens-Fräkmüntegg-Pil. Kulm) 50% off
RB Rigi-Bahn 50% off
SMF-lsm Stöckalp - Melchsee - Frutt 25% off
SMtS St-Imier - Mont-Soleil
SthB Stanserhornbahn
SZU Sihltal - Zürich - Uetliberg

Passholders also get 50% off many lake steamer services.

See full list here.
Swiss railways offering free travel & those only giving a discount, at a glance:

The easiest way to understand is to see this map of Switzerland's rail network. Solid red line = free travel with a Eurail or Interrail pass. Dotted red line = Discount on regular fares give to passholders. Grey lines (if within Switzerland) = no free travel or discount. Common mistake: The dashed red lines are tunnels, not to be confused with the dotted red lines!

Help with train times

Check train times in Switzerland at www.sbb.ch - their journey planner covers all operators, not just SBB.

See international train times & routes from Switzerland

Using a pass within Switzerland

Using a Eurail or Interrail pass in Switzerland is easy, as seat reservations are not required for any journey wholly within Switzerland, you just hop on, sit in any empty seat and show your pass when asked. This even goes for international TGV-Lyria and ICE trains on the Swiss domestic part of their journey, where they form part of the regular-interval Swiss domestic train service.
There are only a handful of exceptions, you must pay to make a seat reservation for certain narrow-gauge panoramic trains aimed at tourists, including the famous Glacier Express between Zermatt & St Moritz, the Bernina Express between Chur, St Moritz & Tirano, the Gotthard Panoramic Express, and the Golden Pass Panoramic trains between Montreux & Zweisimmen.
How to make an online reservation for the Glacier Express if you have a railpass.
How to make an online reservation for the Bernina Express if you have a railpass.

Switzerland ► Paris & France

TGV-Lyria: Zurich, Basel, Lausanne or Geneva to Paris by TGV-Lyria high-speed train

Reservation is compulsory, passholder fee €29 in 2nd class, €39 in 1st class.

Passholder places shouldn't run out as they're taken from the most expensive price bucket.

You can make TGV-Lyria reservations online at Raileurope.com as explained here or using the Eurail/Interrail reservations service.

The reservation is emailed to you in minutes, it can be printed out or shown on your phone.

If you can book 2-3 months ahead, regular advance-purchase tickets start at €29 booked at www.thetrainline.com and might be cheaper.

How to avoid paying these high TGV-Lyria fees:

If you're happy paying the TGV-Lyria reservation fee, fine, it's fast, it's direct, it's comfortable. But if not, you can travel from Switzerland to Paris avoiding TGV-Lyria by taking a TER regional train from Basel SBB to Mulhouse then another TER regional train from Mulhouse to Paris, no reservation necessary for either train. You can find times using int.bahn.de, simply click Mode of transport and select Local transport only.

Similarly, you can take a TER regional train from Geneva to Lyon (no reservation required & no fees) then use one of several TER Lyon-Paris trains (no reservation required, no fees, but they take 5h rather than 2h by TGV). You can find Geneva-Lyon & Lyon-Paris TER times using int.bahn.de, click Mode of transport and select Local transport only.
TER regional trains: Geneva to Lyon, Basel to Mulhouse & Strasbourg by TER regional train

No reservation necessary or possible, hop on, find any empty seat & show your pass when asked.

Switzerland ► Amsterdam & the Netherlands

Nightjet sleeper: Zurich & Basel to Amsterdam by Nightjet sleeper train: See passholder prices.
Passholder reservations for Nightjet sleeper trains can be made online at the ÖBB website using Method 1, see the instructions below.
You can reserve a seat in the Intercity cars attached to this overnight train for around €5 using the German Railways website, see instructions here. However, a seat is a false economy, always pay for a couchette or sleeper unless they are fully-booked.

Switzerland ► Italy

EuroCity trains: Zurich, Basel, Bern, Luzern, Lugano, Geneva to Milan by direct EuroCity (EC) train:

A passholder reservation fee must be paid, €13 in both classes.

Option 1, book at Raileurope.com as explained here. Raileurope is top choice to make reservations on these Switzerland-Italy EuroCity trains because (a) at the time I write this they charge no booking fee, just the reservation cost and (b) for these trains you can select your seat from a seat map, the only retailer to offer this. It's e-ticketed, the reservation is emailed to you in minutes.

Option 2, strange as it may seem, you can make passholder reservations for these trains at the Austrian Railways website www.oebb.at using method 1 explained here. There's no booking fee, but seats are assigned with no choice. It will book Italian high-speed & InterCity trains this way, but not sleepers or couchettes on night trains.

Option 3, you can also make passholder reservations using the Eurail/Interrail reservations service. There's a small booking fee. Seats are assigned with no choice. The reservation is e-ticketed and emailed to you in minutes.

To avoid the need for reservations, use Swiss domestic trains to Domodossola or Lugano, then use regional trains such as the hourly TILO regional express from Lugano to Milan Centrale. It's just a little slower and not as comfortable.

Regional trains, for example Milan-Domodossola-Brig or TILO Milan-Lugano-Locarno.

No reservation necessary or even possible on regional trains (marked R or RE in timetables), just hop on, sit anywhere and show your pass when asked.
Bernina route: Zurich, Chur & St Moritz to Varenna & Milan via the scenic Bernina route:

No reservation is needed on the regular hourly Swiss local trains to Tirano, just hop on and show your pass. No reservation needed on the two-hourly Italian regional train from Tirano to Milan.

Only if you choose to use the Chur-Tirano Bernina Express panoramic train is a seat reservation compulsory, you can make this online as shown here.
Centovalli Railway (FART): Locarno-Domodossola.

Passes are valid on the beautifully scenic Centovalli Railway, but a €1.50 supplement must be paid at the station before boarding. Reservation is optional (but recommended), this costs €4 and can be made online at prenota.vigezzinacentovalli.com. Select Seat reservation and then (as Interrail/Eurail is not specifically listed in their drop-down box) select Swiss Pass as your ticket type.

Switzerland ► Austria

Railjet trains: Zurich to Innsbruck, Salzburg or Vienna by railjet train:

Reservation is optional, you can hop on any train and simply show your pass. However, reserving a seat is a good idea as it's a long journey, especially at busy times such as Friday or Sunday afternoons.

You can reserve a seat for around €3 at the ÖBB (Austrian Railways) website using Method 2, see the instructions here.
Nightjet sleeper: Zurich to Vienna by Nightjet sleeper train: See passholder prices.
Passholder reservations for Nightjet sleeper trains can be made at the Austrian Railways website using Method 1, see the instructions here.

Switzerland ► Germany

Intercity, EuroCity & ICE: Switzerland to Germany by InterCity, ICE or EuroCity train:

Various InterCity, ICE & EuroCity trains link Germany with Switzerland. Reservation is optional, you can just hop on, sit in any empty unreserved seat & show your pass when asked. However, trains can get busy especially in summer, so reserving a seat is a good idea.

You can reserve a seat for around €5 at the DB (German Railways) website, see the instructions below.

Update: In summer from 1 June to 1 September, reservation is compulsory on these cross-border trains. If you find the German Railways website has had seat-only reservations disabled for this period, try using the Austrian Railways website (use Method 2, see the instructions here
Nightjet sleeper: Zurich or Basel to Berlin, Hamburg & Germany by Nightjet sleeper train: See passholder prices.
Passholder reservations for Nightjet sleeper trains can be made at the Austrian Railways website using Method 1, see the instructions here.

Switzerland ► Prague & Czechia

Sleeper train: Zurich to Prague by EuroNight sleeper train (both routes)
With 2nd class pass, bed in 3-berth sleeper €45, bed in 2-berth sleeper €58, bed in single-berth sleeper €110. With 1st class pass, bed in 3-berth deluxe sleeper with shower & toilet €45, bed in 2-berth deluxe sleeper with shower & toilet €58, bed in single-bed deluxe sleeper with shower & toilet €110.
Passholder reservations for the sleeper trains from Zurich or Basel to Prague can be made online at the Czech Railways website www.cd.cz, with no added booking fee. Before running the enquiry, click where it says 1 x Adult 26-64 No discount card then click on No discount card , click Interrail and Eurail Pass then select the one you have. You print your own ticket or can show it on your phone.
Daytime trains: Zurich to Prague by daytime trains with a change at Munich or Linz
None of the daytime trains Zurich-Linz, Linz-Prague or Zurich-Munich, Munich-Prague require reservations, you can just hop on and show your pass when asked. Seat reservations are optional, if you want a reserved seat, make a normal seat reservations from Linz or Munich to Prague at the Czech Railways website as shown here. Then make a normal seat reservations from Zurich to Munich at the German Railways website as shown here, or from Zurich to Linz at the Austrian Railways website as explained here, using Method 2.

Switzerland ► Budapest & Hungary

Railjet trains: Zurich to Budapest by railjet train

Seat reservation is optional, but it's a long journey so reserving a seat is a good idea. You can make a seat reservation for around €3 at the ÖBB (Austrian Railways) website using Method 2, see the instructions here.
Sleeper train: Zurich to Budapest by EuroNight sleeper train
Couchette in 6-berth €44, couchette in 4-berth €54, bed in 3-bed sleeper €69, in 2-bed €94, in single-bed €169, all accommodation types can be booked with a 2nd class pass.

Passholder reservations for sleepers or couchettes can be made online at the ÖBB website using Method 1, see the instructions below.

Switzerland ► Slovenia & Croatia

Sleeper train: Zurich to Ljubljana & Zagreb by sleeper train
Couchette in 6-berth €29.90, couchette in 4-berth €34.90, bed in 3-bed sleeper €64.90, in 2-bed €109.90, in single-bed €234.90.

Prices vary slightly according to demand. All types of couchette or sleeper can be booked with any class of pass.

Passholder reservations for sleepers or couchettes can be made online at the ÖBB website using Method 1, see the instructions below.

Turkey

What's covered?

Interrail & Eurail passes give unlimited travel on TCDD = Turkish Railways ebilet.tcddtasimacilik.gov.tr.

That includes all domestic local & mainline trains run by TCDD in both European & Asian Turkey and (if you've a global pass) international trains to or from Bulgaria & Romania run jointly by TCDD & its partner railways BDZ (Bulgaria) and CFR (Romania).

Help with train times

See international train times & routes from Istanbul

See train times for key domestic routes within Turkey

Using a pass on Turkish trains

Reservations are required for all long distance & high-speed trains within Turkey, but reservations are free unless you want a sleeper, for which a charge is made. Reservations cannot be made online or from outside Turkey, just make a free reservation at any main station when you get to Turkey.
Turkish domestic trains can get booked up, especially couchettes and sleepers, so a good option recommended by TCDD customer service themselves is to buy a full price ticket at ebilet.tcddtasimacilik.gov.tr, then exchange it for a free reservation at a TCDD ticket office. Full price tickets can be fully refunded until 15 minutes before departure, 80% refunded after that. More about how to book trains in Turkey online.

Using a pass on international trains

Istanbul to Sofia by sleeper train:

€10 supplement for a couchette in 4-berth compartment or €15 supplement for a bed in a 2-bed sleeper. If you have a 1st class pass, a single-bed sleeper all to yourself costs €35. Cannot be booked online, make a reservation at the station.
Istanbul to Bucharest by through couchette car (summer only):

€14 supplement for a couchette in 4-berth compartment. Cannot be booked online, make a reservation at the station.

How to make reservations

Some train operator websites allow reservation-only bookings for passholders, most don't. And even if they do, it may work for some routes not others.

Interrail/Eurail reservations service

Once you've bought a Eurail or Interrail pass so have a valid pass number, you can make passholder reservations for many trains using the Interrail/Eurail reservations service, including Eurostar, and trains in many countries.

Go to www.interrail.eu or www.eurail.com, click Seat reservations at the top.

Note that this is their website, not the Railplanner app.

Click yes you have a pass, click no you don't have an account, create an account, entering your pass number.

Now use the reservation system journey planner to bring up train departures for the route you want.

There's a booking fee of €2 per person in addition to the reservation cost. Prices shown include the fee, so a €10 reservation is shown as €12.

You'll often see the abbreviation IRT, Integrated Reservation Ticket, it simply means you'll get a ticket and seat reservation combined on one bit of paper rather than two, as would be old-school practice. From a passenger viewpoint, largely irrelevant. And TRN simply means train.

Trains it can book, with an e-ticket

Reservations shown as e-ticket are automated and emailed to you within minutes.

The system will e-ticket passholder reservations for trains in France & Italy including TGVs, Intercités, Intercités de Nuit with couchettes, Frecciarossa, Frecciabianca, Italian Intercity train, Italian Intercity Notte sleeper trains, also for Paris-Barcelona TGVs, Paris-Turin-Milan TGVs, Paris-Brussels-Amsterdam Eurostars, Paris-Switzerland TGV-Lyria and Switzerland-Italy EuroCity trains.

It can also book optional seat reservations in countries such as Germany & Austria, but you can make those more cheaply, without any added fee using the train operator's website.

It can book some trains in Spain, but not all routes.

Trains it can book, but with a paper ticket that needs to be posted to you

Reservations shown as paper ticket have to be posted to you for an extra fee (€9 to the UK, for example), and this obviously takes time.

Hard-copy tickets have to be issued and posted for Budapest-Bucharest daytime & sleeper trains, Berlin-Warsaw & Berlin-Krakow EuroCity trains, Norwegian trains.

Trains it can't book

The system can't book Portuguese trains or trains in the UK, Ireland, Finland, Serbia, Bosnia, Montenegro, Bulgaria, Greece, Turkey. It also can't book Nightjet sleeper trains or Venice-Vienna railjets (but www.oebb.at can book these, see below). It only seems to offer 2nd class reservations on the Munich-Italy Brenner EuroCity trains. In France, it can't book some trains run by the regions, such as Paris-Cherbourg.
Seating choice

Unfortunately, the Interrail/Eurail reservations service doesn't give you any control over what seats you get, not even basic options such as aisle or window, basically you get what you're given (but if you're booking for 2 or more people together, don't worry, you'll all be seated together by default). Nor do you see your car & seat numbers before you pay, so the old trick of opening multiple tabs, running the same enquiry, comparing the seats you're offered with a seat map until you get seats you like won't work. But here are two tips:

How to change your seats on Eurostar: After booking a Eurostar, you can go to the Eurostar website www.eurostar.com and use the Manage booking feature with your surname & booking reference to change your seats to ones you prefer (I recommend seat 61!). See more detailed advice here.

How to change your seats on French trains including TGVs, Paris-Barcelona TGVs, Paris-Milan TGVs, Paris-Switzerland TGV-Lyria: After Having looked at a seat map, if you really don't like the seats you've been given, it's possible to ask SNCF (French Railways) to change them by phone or at a French station. Call SNCF on 00 33 1 84 94 3635, listen through the initial phone menu in French, it will then switch to English and ask you to press #85 for an English speaking agent (please let me know if that changes). Ask nicely and they may be able to change your seats, usually at no charge if done at least 7 days before departure. You'll need your surname and 7-letter SNCF booking reference (dossier de voyage). Lines open 07:00-10:00 French time, 7 days a week.

Reservations and your pass are totally separate and not linked in any way

You can make reservations even before you activate your pass, before specifying travel days or adding any journeys to it. You don't commit yourself to using a pass day merely by making a reservation. You can make multiple reservations for the same route if you're not sure which train you'll catch, or if you make a reservation then change your plans, it does not affect your pass in any way. And if there's (say) 4 of you, all with passes, one of you can make reservations for 4 people this way, no problem. You only need to add the journey in question to your pass (and trigger a pass day on a flexi pass, if it's the first train you're taking that day) when you're about to board the train!

How to make reservations on Eurostar

To make passholder reservations on Eurostar between London and Lille/Paris/Brussels/Amsterdam, see the advice here.

How to make reservations at Raileurope.com

Well-known ticket retailer www.raileurope.com launched passholder reservations in 2023. For the trains they can book, they are a better option than using the Interrail/Eurail reservations service, for several reasons.
How to use it:
Go to www.raileurope.com.
Click Add rail pass below the journey planner and select the type and class of pass you have.
Then simply run a search as if you were buying a ticket. You should now see passholder reservation costs, not normal ticket costs.
You can check passholder availability before buying a pass, but you need a valid pass number to make a booking. Reservations are e-ticketed.
What if you have a one-country pass?
When you select your pass type, only global passes are listed. However, in reality passholder reservations are exactly the same whether for a global pass or a one-country pass. So go ahead and select the relevant global pass type, even if you have a one-country pass, it makes zero difference to the actual reservation! Just make sure that you only reserve trains wholly within that country (obviously).
What if you have an Interrail, but your friend has a Eurail?
When you select your pass type, you have to select either Interrail global pass or Eurail global pass for all passengers. However, in reality passholder reservations are exactly the same whether for Eurail or Interrail, which is why most other retailers have just one combined option labelled Interrail/Eurail. So go ahead and select Interrail global pass for all passengers, even if you have an Interrail and your friend has a Eurail. It makes zero difference to the actual reservation! Just make sure you select the right class for your pass, 1st or 2nd.
If you have a 1st class pass, it will offer you both 2nd class and 1st class reservations in the search results, but it defaults to 2nd class. So if you want a 1st class seat (of course you do!), remember to change the price drop-down to 1st class.
If it won't accept your mobile pass number, simply generate a pass cover number from your mobile pass number using www.eurail.com/en/book-reservations#/generatePassCoverNumber.
What trains can it reserve? Raileurope can do passholder reservations for Eurostar, French trains (including Intercités de Nuit), Italian trains (including Intercity Notte sleepers), TGV-Lyria Paris-Switzerland, TGV Paris-Milan, TGV Paris-Barcelona, and (from 2025) Spanish trains run by Renfe including AVE, Euromed, Alvia, Intercity. If you don't see passholder prices, just normal fares, try another website/method.
Booking fee? They charge no booking fee for low-value reservations, only the cost of the reservation itself. That makes them cheaper than using the Interrail/Eurail reservation service.
The big advantage: Seat choice! You get more seat choice than using the Interrail/Eurail reservation service (which gives no choice at all): Using www.raileurope.com, on French trains you can select seating options such as aisle or window, and upper or lower deck on a TGV Duplex. On Trenitalia trains you can choose your seat from a seat map (this costs an extra €2, same as it does when buying a normal ticket).

How to make reservations at the French Railways website

The French Railways website www.sncf-connect.com no longer sells passholder reservations. Passholder reservations were discontinued in 2020 due to high levels of fraud. You should now use the Interrail/Eurail reservations service.
But you can book by phone if you like, call SNCF telesales on 00 33 1 84 94 3635.

Tip: If they say they can't do pass bookings, be polite but firm, and tell them to use code IR50 for International Interrail bookings and code IR00 for domestic French train bookings. If they refuse, you may need to call back and get someone else!

How to make reservations at the Belgian Railways website

The Belgian Railways site www.b-europe.com can make Interrail & Eurail passholder reservations for Eurostar, Eurostar (formerly Thalys) high-speed trains and most French domestic & international trains including Paris-Switzerland TGV-Lyria, Paris-Milan & Paris-Barcelona TGVs, Brussels-France TGVs.
They charge a small fee per overall booking. They usually offer some seating options, although Raileurope may offer more choice.
Their passholder booking page is www.b-europe.com/EN/Booking/Pass (please let me know if this changes).
Or hover over Plan & book, look under Interrail passes and click Book a seat at pass fare.
You are emailed your ticket.

How to make reservations at the Trenitalia website

The Italian Railways website www.trenitalia.com used to sell passholder reservations on trains in Italy. However, passholder reservations were disabled in 2019 due to high levels of fraud. You should now use the Interrail/Eurail reservations service or www.raileurope.com.

How to make reservations at the German Railways (DB) website

The German Railways website can make reservation-only bookings for seats on most trains within Germany.
It can also make seat reservations on international trains between Germany and BE, NL, CH, AT, DK, PL, CZ, SK, HU.

It can also make seat reservations on some journeys across Germany, for example NL/BE/LU <> CH/DK/PL/CZ; CH<>DK/CZ etc.
It cannot make reservation-only bookings for Nightjet sleeper trains, you need the Austrian ÖBB website for that as shown below.
It should NOT be used to make seat reservations on ICE/TGV trains to/from France as it can only sell regular seat reservations and on this particular route a regular seat reservation is insufficient, you need a special (more expensive!) passholder reservation.

Booking opens up to 6 months ahead, although this varies.
Go to int.bahn.de. Set up an enquiry, but instead of clicking the red Search button, click the Book seat only link underneath.
Seat reservations cost €5.20 per seat in 2nd class, €6.50 in 1st class.
You are only charged one fee per journey, even if your journey involves two or more connecting trains.
You can usually select seats from a seat map when reserving seats on a German IC or ICE train using int.bahn.de.

Tip: For journeys to/from Austria, seat reservations only cost €3 if you make them at the ÖBB (Austrian Railways) website as shown below, and you usually get to select seats from a seat map on railjet trains if you reserve them through ÖBB.
Tip: For journeys to/from the Czech Republic, seat reservations only cost €3 if you make them at the CD (Czech Railways) site as shown below, and you usually get to select seats from a seat map on EuroCity trains between Berlin or Dresden & Prague if you reserve through CD.
Tip: You can make domestic reservations within Germany for only €3 using the ÖBB or CD websites, with two downsides: 1. You won't get seat selection from a seat map when booking German IC/ICE trains this way. 2. ÖBB & CD charge €3 for each train whereas int.bahn.de charges one reservation fee for your whole journey even if it involves multiple trains.

How to make reservations at the Austrian Railways (ÖBB) website

What can it reserve?
The Austrian Railways website shop.oebbtickets.at can make passholder reservations in either direction for:

- Nightjet sleeper trains;

- EuroNight sleeper trains including Munich-Zagreb, Munich-Budapest, Zurich-Budapest, Zurich-Zagreb, Berlin-Krakow, Berlin-Budapest;

- The Dacia Express sleeper train between Vienna/Budapest and Sighisoara/Brasov/Bucharest;

- Railjet trains between Vienna & Venice, these have a compulsory passholder fee and optional seat reservation;

- EuroCity trains between Munich/Innsbruck & Verona, Bologna, Venice, also with compulsory passholder fee & optional seat reservation;

- It can also make normal (usually optional) seat reservations on trains to, from or within Austria, for example Vienna-Budapest, Vienna-Zurich, Vienna-Munich, Innsbruck-Zurich or Salzburg-Munich.

There are two different methods, use the right one.

To make special passholder reservations on Nightjet sleeper trains, certain EuroNight sleeper trains, the Vienna-Venice railjets & Munich-Italy EuroCity trains, use Method 1.

To make normal seat reservations (which is all passholders need on most Austrian routes, for example Munich-Vienna, Vienna-Prague, Vienna-Budapest, Salzburg-Vienna, Vienna-Krakow/Warsaw) use Method 2.

If you're not sure which to use, read the country-by-country information above to see what your specific route/train requires.
Method 1, the Interrail/Eurail discount method

Use this method to make passholder reservations on Nightjet sleeper trains, certain EuroNight sleeper trains or EuroCity/railjet trains between Munich/Austria & Italy. Booking opens up to 6 months ahead, but often less than this.

1. Go to shop.oebbtickets.at (please let me know if this link stops working) and set up a journey enquiry as if you were buying a ticket.

2. Where it says 1 x adult, click Change. Enter the number of passengers, and for each passenger under Adult no discount, click Add discount.

3. In the Search discounts facility, start typing Inter or Eurail and it'll bring up Interrail/Eurail - Globalpass. Select & confirm.

4. Leave the Seat reservation only box un-ticked, because this method books what the system sees as a special fare, not reservation-only.

5. Now click the red Find button run the enquiry

6. If booking a sleeper train, you should now see a €13.50 (approx) passholder seat reservation fee, which you can change to couchette or sleeper, then modify the type of couchette and sleeper to what you want. The passholder couchette or sleeper reservation price should now correspond to those quoted on this page. Remember that prices are per person per bed, not per compartment - if you book 2 people in a double sleeper or 4 people in 4-berth couchettes, you get a whole compartment, but if you book less than the number of beds in a sleeper or couchette compartment (for example, 2 people in a 3-berth sleeper), other passengers may be booked in with you in the vacant beds. You print out your reservation or can show it on your mobile.

7. If booking a railjet train between Munich/Innsbruck/Vienna & Italy, you should now see the €10 passholder surcharge. You can add an optional seat reservation for €3, strongly recommended, especially in summer. If you have a 1st class pass, click on the €5 1st class upgrade to get the €15 first class passholder fee. On the Vienna-Venice route, if you have a 1st class pass you can further upgrade to luxurious railjet business class for another €15 if you like - you won't regret it!
Warning: If you have a 2nd class pass, don't upgrade to 1st class. The standard wording used by the ÖBB website makes it look like a tempting €5 upgrade to 1st class. In fact, it's the 'upgrade' from the 2nd class passholder fee to the 1st class passholder fee. Don't buy a 1st class passholder fee if you only have a 2nd class pass! Similarly, the upgrade to business class on a railjet is an upgrade to the 1st class passholder fee - only buy it if you have a 1st class pass.
In your basket, if you click for price details, it will show the Brenner route passholder fee as Aufpreis Brennerverkehr Passzuschlag 1. It will show the Vienna-Venice route passholder fee as Tarvisioverkehr Pass1. You print out your reservation or can show it on your mobile.

Method 2, the 'seat reservation only' method

Use this method to make normal seat reservations on trains between Austria & Switzerland, Germany, Czechia, Slovakia, Poland, Hungary, Romania. Seat reservation is usually optional on these trains, if you want a reserved seat it's the same process as for any other traveller with an existing ticket who wants to reserve a seat. In other words, on these trains/routes it's not a special passholder reservation, just a normal seat reservation. Booking opens up to 6 months ahead, although it can often be less than this.

1. Go to shop.oebbtickets.at (please let me know if this link stops working) and set up your journey enquiry.

2. Tick the Seat reservation only box.

3. Click the red Find button to run the enquiry.

4. Seat reservations normally cost €3 per seat. Make sure you book the same class (1st or 2nd) as your pass. You print your reservation or can show it on your phone.

How to make reservations at the Czech Railways (CD) website

The Czech Railways website can make reservation-only bookings for seats and in some cases couchettes & sleepers on trains to & from Prague & the Czech Republic. In some cases it works for reservations wholly outside the Czech Republic too, for example Bratislava to Budapest or Budapest to Krakow. Seat reservations normally cost €3 per seat. Booking usually opens up to 60 days ahead.
Go to www.cd.cz and run an enquiry for your journey. In the search results, look for the train you want.
In the green Purchase a ticket box, click the down arrow. Then select Purchase reservations only.
Go ahead and make a reservation, you simply print it out.

How to make reservations at the Hungarian Railways (MAV) website

Go to jegy.mav.hu and switch HU to EN at upper right for English.
Set up an enquiry. Click Passengers and discounts and enter your date of birth.
Then click + Add discount and select Interrail/Eurail/Pass. Then run the enquiry.
Find the train you want and click on the price. If it's a night train, you should then see a range of sleeping accommodation. Click on the one you want and you should then see the reservation-only price.
You can print the reservation or in most cases show it on your phone or in the MAV app.

How to make reservations at the Polish Railways (PKP Intercity) website

The PKP Intercity website www.intercity.pl (sales page ebilet.intercity.pl) can make passholder reservations on trains within Poland, on EuroCity trains between Berlin & Poland, and on the direct train between Mockava (Lithuania) and Warsaw.

Booking for Polish domestic trains opens 30 days before departure.

You can select your seat from a seat map on Polish domestic trains if you book this way.

There's no added booking fee, it normally costs just 3 zloty (€0.70) per seat per train, or 43 zlotys (€10) for an EIP train.

International trains to/from Berlin or Mockava cost around €3.50 per seat.

It can only book seats, it can't book couchettes or sleepers. It can book domestic journeys, but not international ones.
Step 1, go directly to the sales page ebilet.intercity.pl and switch it to English (EN) top right.

Tick the Buy a reservation for your ticket box above the journey planner.

Step 2, it prompts you to log in or register. After registering and/or logging in it returns you to the sales page.

Step 3, under Choose, select Eurail/Interail. Enter your pass number (or make one up, any 6-alpha-numeric seems to work) & validity period.

Step 4, run an enquiry and make a reservation. You can select your seat from a seat map on TLK, IC, EIC and EIP trains.

You print your reservation or can show it on your phone.

Tip: The system is clever enough to stop you making more than one reservation using the same ticket/pass number for trains that are due to be in motion at the same time. If the first train hasn't yet left, log in to your account and cancel the first reservation before making the second reservation. You can't cancel after the train has left, so if you miss it and need to reserve on a later train while the first train is still en route, make a second reservation using a made-up pass number - If it makes you happier, a plausible 'error' of one digit in your actual pass number when making the second reservation, although no-one will check, if you have a valid seat reservation and a valid pass, you'll be fine.
If you have any problems, you can make Polish domestic seat reservations for €3 at the Czech Railways website as shown here.

How to make a eurail or interrail seat reservation on a Polish train

Above, this is the Buy a reservation for your ticket box. If you don't see it, play around until you find a page where it appears.

How to make reservations at the Danish Railways (DSB) website

It's usually easiest to make reservations for the international Hamburg-Copenhagen route using the German Railways website int.bahn.de.
Seat reservations usually open 2 months ahead, look for the Book seat only toggle. If booking isn't open or can't be done for any other reason it'll say so. You print your reservation or can show it on your phone. I prefer using bahn.de for this route as it lets you specify options such as window seat.

If bahn.de doesn't work for you or you want a reservation on a Danish domestic train, you can make seat reservations at the Danish Railways website www.dsb.dk:
Click In English right at the bottom of the page, then scroll back up & click Train ticket to Europe. Now click Buy your international seat reservation and run the relevant enquiry.
You'll notice that they have sub-contracted this function to a white-labelled version of the Belgian Railways international website, here's a direct link to the international reservations page: travel.b-europe.com/dsb-rail/en/reservation-only (please let me know if it changes). The seat reservation costs around 30Kr, about €4. The fact that a price is shown doesn't mean booking is open, you only know that it's open and space is available when you click to reserve. You print your reservation or can show it on your phone.

How to make reservations at the Swedish Railways (SJ) website

You can make reservations for Swedish domestic and international trains (including Copenhagen-Stockholm, Stockholm-Oslo, and the Berlin/Hamburg-Stockholm SJ sleeper) at the Swedish Railways website www.sj.se. There's no added booking fee, although it's occasionally been known to struggle with overseas credit cards.
Go to www.sj.se, switch it to English, click Search journey and fill in the From and To boxes.

Now the important bit: Click Customise against each passenger.

Then toggle on Travels with travel card. Then scroll down and select Interrail or Eurail.

When the results appear, click on the train you want. The details for that train appear.

Make sure you select the correct class: If you have a 2nd class pass, leave 2nd class selected. if you have a 1st class pass, change it to 1st class (with a 1st class pass you can make a reservation in either class, if there's no availability in 1st you can always go 2nd).
Tip: If booking a sleeper on the Berlin/Hamburg-Stockholm night train, there's a glitch. The Interrail/Eurail price is correctly shown in the first column marked Bed in a sleeping compartment with Interrail, Eurail. However, the price for a Bed in a private sleeping compartment is not correct because it does not include the Interrail/Eurail discount. Therefore, you should always select the first column, even if you want a private compartment for two of you. If you have 2 passengers selected, then select the first column Bed in a sleeping compartment with Interrail, Eurail, then select all male, the system will normally put you together in your own private compartment anyway. Your are shown your berth numbers before payment so you can confirm this: The first digit should be the same, the second digit should be either 1 & 5 or 2 & 6, for example 41 & 45 are together in one 2-bed sleeper, and so are 52 & 56. See the way sleeper berths are numbered.

How to make reservations at the Leo Express website

Leo Express is a privately-owned open-access operator operating in the Czech Republic and Poland.
2nd class passes entitle you to free travel in economy class. 1st class pass entitles you to free travel in business class. A reservation is required but can be made for free online or in person at the Leo Express offices at Prague and Ostrava.
To make a passholder reservation online, go to www.leoexpress.com and use the journey planner.
Click on the number of passengers field and a box appears to the right which says You can apply further discounts. Click on the Discounts link and select Interrail/Eurail. This applies a 100% discount.

Tips for booking hotels

I recommend www.booking.com as you can usually book hotels with free cancellation. That means you can sort your hotels without any risk months before train bookings open, and even change your plans at no cost usually up to 24 hours before checking into the hotel. Any hotels, guesthouses or B&Bs with a review score over 8.0 are unlikely to disappoint.

Hotels will almost always look after your bags for free if you need to check out and catch an afternoon or evening train, or if you arrive in the morning before you can check in to your room.

My favourite hotel search: www.booking.com

Booking.com is my favourite hotel booking site and I generally use it to book all my hotels in one place. I've come to trust booking.com's review scores, you won't be disappointed with any hotel that scores 8.0 or more. Crucially, booking.com usually lets you book with free cancellation, which means you can confirm accommodation risk-free before train booking opens and/or you can hold accommodation while you finalise your itinerary and alter your plans as they evolve - a feature I use all the time when planning a trip. I never book hotels non-refundably!

Backpacker hostels

www.hostelworld.com: If you're on a tight budget, don't forget about backpacker hostels. Hostelworld offers online booking of cheap private rooms or dorm beds in backpacker hostels in Paris and most other European cities at rock-bottom prices.

Travel insurance & VPN

Always take out travel insurance

You should take out travel insurance with at least £1m or preferably £5m medical cover from a reliable insurer. It should cover trip cancellation and loss of cash & belongings up to a reasonable limit. These days, check you're covered for covid-19-related issues, and use an insurer whose cover isn't invalidated by well-meant but excessive Foreign Office travel advice against non-essential travel. An annual policy is usually cheapest even for just 2 or 3 trips a year, I have an annual policy with Staysure.co.uk myself. Don't expect travel insurance to bail you out of every missed connection, see the advice on missed connections here. Here are some suggested insurers, I get a little commission if you buy through these links, feedback always welcome.

www.staysure.co.uk offers enhanced Covid-19 protection and gets 4.7 out of 5 on Trustpilot.

www.columbusdirect.com is also a well-know brand.

If you live in the USA try Travel Guard USA.

Get an eSIM with mobile data package

Don't rely on WiFi, download an eSIM with a European mobile data package and stay connected. Most newer mobile phones can download a virtual SIM including iPhone 11 & later, see device compatibility list. There's no need to buy a physical SIM card! Maya.net is a reliable eSIM data retailer with a 4.5 out of 5 Trustpilot rating and a range of packages including unlimited data.

Get a Curve card for foreign travel

Most banks give you a poor exchange rate then add a foreign transaction fee on top. A Curve MasterCard means no foreign transaction fees and gives you the mid-market exchange rate, at least up to a certain limit, £500 per month as I write this. The money you spend on your Curve card goes straight onto one of your existing debit or credit cards. And you can get a Curve card for free.

How it works: 1. Download the Curve app for iPhone or Android. 2. Enter your details & they'll send you a Curve MasterCard - they send to the UK and most European addresses. 3. Link your existing credit & debit cards to the app, you can link up to two cards with the free version of Curve, I link my normal debit card and my normal credit card. 4. Now use the Curve MasterCard to buy things online or in person or take cash from ATMs, exactly like a normal MasterCard. Curve does the currency conversion and puts the balance in your own currency onto whichever debit or credit card is currently selected in the Curve app. You can even change your mind about which card it goes onto, within 14 days of the transaction.

I have a Curve Blue card myself, it means I can buy a coffee on a foreign station on a card without being stung by fees and lousy exchange rates, just by tapping the Curve card on their card reader. The money goes through Curve to my normal debit card and is taken directly from my account (in fact I have the Curve card set up as payment card on Apple Pay on my iPhone, so can double-click my phone, let it do Face ID then tap the reader with the phone - even easier than getting a card out). I get a little commission if you sign up to Curve, but I recommend it here because I think it's great. See details, download the app and get a Curve card, they'll give you £5 cashback through that link.

Get a VPN for safe browsing. Why you need a VPN

When travelling you may use free public WiFi which is often insecure. A VPN encrypts your connection so it's always secure, even on unsecured WiFi. It also means you can select the geographic location of the IP address you browse with, to get around geoblocking which a surprising number of websites apply. See VPNs & why you need one explained. ExpressVPN is a best buy with a 4.7 out of 5 Trustpilot ranking which I use myself - I've signed up as an ExpressVPN affiliate, and if you go with expressvpn.com using this link you should see a special deal, 3 months free with an annual subscription. I also get some commission to help support this site.

Carry an Anker powerbank

Tickets, reservations, hotel bookings and Interrail or Eurail passes are often now held on your mobile phone. You daren't let it run out of power, and you can't always rely on the phone's internal battery or on being near a power outlet. I always carry an Anker powerbank which can recharge my phone several times over. Buy from Amazon.co.uk or buy from Amazon.com.

Touring cities? Use hill walking shoes!

One of the best things I've done is swap my normal shoes for hill-walking shoes, in my case from Scarpa. They're intended for hiking across the Pennines not wandering around Florence, but the support and cushioning for hiking works equally well when you're on your feet all day exploring foreign cities. My feet used to give out first and limit my day, now the rest of me gives up before they do!

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Interrail & Eurail

Reservations guide

Train travel UK & Ireland...

Train travel in Europe...

Train travel in Asia...

Train travel in Africa...

Train travel in America...

Train travel in Australasia

On this page I explain...

Select the country where the train starts

What's covered?

Help with train times

Using a pass within Austria

Austria ► Belgium

Austria ► France

Austria ► Germany

Austria ► Netherlands

Austria ► Switzerland

Austria ► Italy

Austria ► Hungary

Austria ► Czech Republic

Austria ► Slovakia

Austria ► Poland

Austria ► Slovenia, Croatia, Serbia

Austria ► Romania

What's covered?

Help with train times

Using a pass within Belgium

Belgium ► Great Britain

Belgium ► France

Belgium ► Netherlands

Belgium ► Germany

Belgium ► Austria

Belgium ► Luxembourg

Belgium ► Czech Republic

What's covered?

Help with train times

What's covered?

Help with train times

Using a pass on national trains

Using a pass on international trains

What's covered?

Help with train times

Using a pass within Croatia

Using a pass on international trains

Czech Republic

What's covered?

What's not covered

Help with train times

Using a pass within the Czech Republic

Czech Republic ► Belgium

Czech Republic ► Netherlands

Czech Republic ► Germany

Czech Republic ► Austria

Czech Republic ► Switzerland

Czech Republic ► Hungary

Czech Republic ► Slovakia

Czech Republic ► Poland

What's covered?

Other pass benefits

Help with train times

Using a pass within Denmark

Denmark ► Germany

Denmark ► Sweden

What's covered?

Other pass benefits

Help with train times

Using a pass on national trains

What's covered?

Other pass benefits

Help with train times

Using a pass within Finland

What's covered?

What's not covered?

Other pass benefits

Help with train times

How to make reservations for France

France ► Great Britain

France ► Belgium

France ► Netherlands

Train travel
UK & Ireland...

Train travel
in Europe...

Train travel
in Asia...

Train travel
in Africa...

Train travel
in America...

Train travel
in Australasia