Time Calculator

Add or subtract time durations

This time calculator adds or subtracts two or more durations entered as hours, minutes and seconds. It is useful for totalling work shifts, adding up video or music run times, splitting lap times or working out how much time is left. It works with durations, not clock times, so there is no AM/PM setting.

How to use it

1. Choose Add Times or Subtract Times.
2. Type hours, minutes and seconds into each row. Empty boxes count as zero.
3. Click + Add Time Entry for more rows, or × to remove one (at least two rows stay).
4. Read the result, which updates as you type.

How it works

Every row is converted to seconds: hours × 3600 + minutes × 60 + seconds. In add mode all rows are summed. In subtract mode the later rows are taken away from the first row. The total is then shown as HH:MM:SS, decimal hours (4 decimal places), total minutes (rounded), total seconds, and, when the result is 24 hours or more, a days : hours : minutes : seconds breakdown.

Example (add): 1:45:30 + 2:30:45 = 6,330 + 9,045 = 15,375 seconds = 04:16:15, or 4.2708 hours and 256 minutes.

Example (subtract): 8:00:00 − 0:45:00 − 1:15:30 = 28,800 − 2,700 − 4,530 = 21,570 seconds = 05:59:30.

Good to know

• Only whole numbers are used. A value like 1.5 hours is read as 1 hour, so enter 1 hour 30 minutes instead.
• You can type more than 59 in the minutes or seconds box — 90 minutes is counted as 1 hour 30 minutes.
• If you subtract more than the first row, the result is shown in red with a minus sign.
• Decimal hours are handy for timesheets and billing: 04:16:15 is 4.2708 hours.

Frequently asked questions

How do I convert HH:MM:SS to decimal hours?

Divide the total seconds by 3600, or use hours + minutes ÷ 60 + seconds ÷ 3600. The calculator shows this as Total Hours.

Can I add more than two times?

Yes. Add as many rows as you need. In subtract mode, every row after the first is subtracted from it.

Does it handle days?

Results of 24 hours or more also show an extended breakdown in days, hours, minutes and seconds. The HH:MM:SS value keeps counting hours past 24.