Time Calculator

Add and subtract hours, minutes and seconds, add a duration to a clock time and find the time between two clock times across midnight.

What to find:

Add and subtract time durations

Add time to a clock time (or subtract)

Time between two clock times

Write time as h:mm or h:mm:ss, for example 1:30 or 0:45:20. Use + and − in the expression: 1:30 + 2:45 − 0:20.

Test yourself

The time calculator adds and subtracts durations in hours, minutes and seconds, adds time to a clock time (for example, "22:30 + 3 h 45 min") and finds the time between two clock times, including across midnight. The solution shows carrying over 60, as in column addition.

How to add time

Add hours, minutes and seconds separately, then carry the excess: 60 seconds = 1 minute, 60 minutes = 1 hour.

Example. 1 h 30 min + 2 h 45 min = 3 h 75 min; 75 min = 1 h 15 min, so the answer is 4 h 15 min.

When subtracting and there are not enough minutes, borrow 1 hour = 60 minutes: 5:10 − 2:40 = 4:70 − 2:40 = 2:30. With both pluses and minuses it is easier to convert everything to seconds (1 h = 3600 s, 1 min = 60 s), calculate and convert back.

Clock time and midnight

If the sum exceeds 24 hours, subtract 24 h — this is a time on the next day: 22:30 + 3:45 = 26:15 = 02:15 the next day.
If the difference of two clock times is negative, the interval crosses midnight — add 24 h: from 22:15 to 06:40 = 06:40 − 22:15 + 24:00 = 8 h 25 min.