How long will my Japan Rail Pass be valid for?

Please note that you will have to exchange the voucher for the actual ticket in Japan at the latest 90 days after your purchase. You will choose the starting date when you will exchange it.

Once your voucher has been exchanged and your Japan Rail Pass activated, your Japan Rail Pass is valid for 7, 14 or 21 full days.

The Japan Rail Pass validity is calculated in days, not in hours, so it does not matter what time you first use your pass. 

Therefore, if you have a 7 days Japan Rail Pass and you start using it on March 1st, whatever the time, this will count as day 1, and you will be able to use until March 7th midnight.