Common trains that require mandatory seat reservations include France’s TGV, Spain’s AVE, Italy’s Frecciarossa, overnight trains, and some Swiss Panoramic trains. If you don’t have a seat reservation for these, you cannot board the train, even with a valid pass.

To check whether your train requires a reservation, the most accurate method is to use the official Eurail app — Rail Planner.

• How to check: Open the Rail Planner App, enter your travel date, departure, and arrival cities
• In the search results, check for one of the following labels:
  • Seat reservations required → This train requires a reservation. You must reserve a seat to board.
  • Seat reservations optional → May or may not require a reservation depending on the season or route. Take note of the train type, then go to More > Rail Network Guides > Select country in the app to check further details.
  • Seat reservations recommended → A reservation is recommended (e.g., for busy routes or long-distance journeys), but you can still board without a reservation.