Add Hours and Minutes to a Time Calculator

How it works

end = start + (days × 1,440 + hours × 60 + minutes) minutes (or × 60 for seconds) · subtract = start − duration · clock time = end mod 1,440 · day shift = ⌊end ÷ 1,440⌋ · end date = start date + day shift

Every time is converted to minutes after midnight (seconds when you use them). The duration is added, or subtracted, and the total is taken modulo 1,440, the minutes in a day, to fold it back onto the clock. The whole-day part of the division says whether the result falls on the same day, the next day or several days away, which matters for shifts, flights and medication schedules that cross midnight. Because the arithmetic is in plain minutes, it never trips over the AM/PM boundary. You can type the start in 24-hour form or with AM/PM, use decimal hours (2.5 = 2 h 30 min) or more than 59 minutes, and add days and seconds under More options. Give a start date to get the end date and weekday, and set a repeat count to list every time in a regular interval, such as doses every 6 hours.

Worked example

Start at 09:00 and add 3 hours 45 minutes: 9 × 60 = 540 minutes, plus 225 minutes, is 765 minutes, which is 12:45 PM on the same day. A night shift that starts at 10:30 PM and lasts 8 hours 15 minutes ends at 1,350 + 495 = 1,845 minutes. Taking away one day (1,440) leaves 405 minutes, so it ends at 6:45 AM the next day. Subtracting works the same way: 2:15 AM minus 3 hours is 11:15 PM the previous day.

Frequently asked questions