Time duration calculator
Find how long it is between two clock times, or add and subtract a list of times, with the answer in hours, minutes and seconds and in decimal hours.
- 100% free
- Runs in your browser
- No uploads
Duration
Enter a start time and an end time.
- Runs on your deviceEvery tool works directly in your browser. No files are uploaded.
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How to use the time duration calculator
- Pick a mode. Between two times measures from a start time to an end time. Add or subtract totals a list of durations.
- Type the times. Use 24-hour or 12-hour times such as 14:30 or 2:30 pm. Add seconds as 14:30:15 when you need them.
- Add dates if the span is long. For anything longer than a day, tick Add dates and choose the start and end dates.
- Read or copy the result. You get h:mm:ss, the duration in words, decimal hours, total minutes and total seconds.
How the duration is worked out
Every time is turned into seconds after midnight. The calculator subtracts the start from the end. When the end is earlier, it adds 24 hours, so an overnight span such as 23:45 to 0:15 is 30 minutes, not a negative number. Two equal times are 0, unless you say the end is on the next day, which makes it 24 hours.
With dates, the whole days between the two dates are added at 24 hours each. In the Add or subtract mode, each line is added or taken away in seconds, and the total is only converted back to hours, minutes and seconds at the end. Decimal hours are rounded to 2 places, halves up, from the exact number of seconds.
The duration boxes accept 1:30 (an hour and a half), 1:30:15, 2h 15m, 45m, 30s and plain decimals such as 1.5, which means 1.5 hours.
Examples
| Calculation | Duration | Decimal hours |
|---|---|---|
| 9:15 to 17:45 | 8:30:00 | 8.50 |
| 22:30 to 6:15 (overnight) | 7:45:00 | 7.75 |
| 8:13:20 to 17:17:05 | 9:03:45 | 9.06 |
| 1:45:30 + 2:20:45 − 0:30 | 3:36:15 | 3.60 |
| Mon 9:00 to Wed 8:00 | 47:00:00 | 47.00 |
Tips and common mistakes
Don't subtract times like decimals. 5:10 minus 2:50 is not 2.60. Borrow an hour as 60 minutes: it's 2:20.
1:30 is not 1.30 hours. An hour and a half is 1.5 decimal hours. Type 1:30 for hours and minutes, or 1.5 for decimal hours.
Working out a shift? The hours worked calculator takes off unpaid breaks, and the time card calculator adds up a whole week of shifts. For days between dates rather than hours, use the date calculator.
Frequently asked questions
How do I calculate the time between two times?
Subtract the start time from the end time. If the end is earlier on the clock, add 24 hours, because it's on the next day. From 9:15 to 17:45 is 8 hours 30 minutes; from 22:30 to 6:15 is 7 hours 45 minutes.
How do I add hours and minutes together?
Add the minutes, carry every 60 minutes over as an hour, then add the hours. 1:45 plus 2:30 is 3 hours 75 minutes, which is 4:15. In the Add or subtract mode, type each time on its own line and the calculator carries the minutes and seconds for you.
How do I convert a duration to decimal hours?
Divide the minutes by 60 and add them to the hours. 7 hours 45 minutes is 7 + 45 ÷ 60 = 7.75 hours. The calculator shows decimal hours under every result; the decimal hours calculator converts in both directions.
Can it work out durations longer than 24 hours?
Yes. Tick “Add dates” and choose a start and end date, or tick “The end time is on the next day” for spans up to 48 hours. In Add or subtract, totals can be any length, such as 125:30:00.
Does it handle daylight saving time?
No. Every day counts as exactly 24 hours. On the night the clocks change, a span that crosses the change is really one hour longer or shorter than shown, so adjust it by hand.