A rail pass day runs from midnight to midnight. You can board as many trains as you like during these 24 hours. For overnight trains that depart after 7 pm, (19h) a rail day will begin at 7 pm (19h) and end the next day at midnight. So, on the overnight trains, you get 5 extra hours and save a night of lodging costs.
A rail pass month is calculated as a calendar month. Here’s an example, a pass that begins on June 18 will expire at midnight on July 17.
These links will take you to country-specific websites where you will be able to buy your Rail Pass and/or your Seat Reservation to accompany your Train Pass:
USA – Argentina – Australia – Brazil – Canada – GCC Countries – Hong Kong – India – Israel – Japan-Jp – Mexico, Central America, Caribbean – New Zealand – Singapore – South Africa – Rest of the world (English) – Rest of the world (Español) – 中国 – 香港 – 日本 – 한국 – 新加坡
European citizens can order the Interrail Pass with these links:
UK – Belgium-Fr – Belgium-Nl France – Germany – Italy – Netherlands – Spain – Switzerland-Fr – Switzerland-De