A travel day is a 24-hour period in which you can travel on trains with your Interrail Pass. It lasts from 00:00 (midnight) to 23:59 on the same calendar day.

In the context of train passes like Eurail or Interrail in 2026, a "travel day" is strictly defined as a calendar day, lasting from 00:00 (midnight) to 23:59 on the same day. It is not a rolling 24-hour window from the time you first board. For example, if you board a train at 10:00 AM on a Tuesday, your travel day expires at midnight that night, not at 10:00 AM on Wednesday. However, there is a helpful "overnight rule": if you board a direct night train that departs before midnight and arrives after midnight, you only need to use one travel day (the day of departure). This allows you to travel for nearly 24 hours while only deducting one day from your pass. For mobile passes, the app automatically tracks this based on the local time of the station where you board, so it is crucial to ensure your phone's clock is synchronized correctly when crossing time zones in Europe.