Time calculator

Add or subtract durations in hours, minutes and seconds.

Formula Date & time

Result (h:mm:ss)

Decimal hours: 4.2500 h
Total minutes: 255 min
Total seconds: 15,300 s

How it works

Both durations are converted to seconds, added or subtracted, and converted back. Minutes and seconds above 59 are allowed and carry over, so 90 minutes counts as 1 hour 30 minutes.

Hours are not wrapped at 24, so the result is a duration rather than a time of day. A negative result means the second duration is longer.

Formula

Seconds = hours × 3600 + minutes × 60 + seconds
Result = first ± second, shown as h:mm:ss

Worked example

1:45:00 plus 2:30:00 is 4:15:00, which is 4.25 hours, 255 minutes or 15,300 seconds.

Questions people ask

How do I add hours and minutes?

Add the minutes and carry every 60 minutes into an hour. 1:45 plus 2:30 is 3 hours 75 minutes, which is 4:15.

Can the result be more than 24 hours?

Yes. The result is a total duration, so 20 hours plus 10 hours is 30:00:00.