Duration Calculator: Hours, Minutes, Seconds to Decimal Hours
Turn any hours, minutes and seconds into a tidy duration, decimal hours, minutes and seconds.
Inputs
- Working
- 1 × 3,600 + 30 × 60 + 0 = 5,400 seconds
- Decimal hours
- 1.5
- Total minutes
- 90
- Total seconds
- 5,400
- Days + hours
- 1h 30m
Use this calculator on your own site
Free embed
- Two lines of HTML, unlimited views
- Shows a small CalculateEveryday bar, with a credit link under the calculator
What each Duration input means
- Hours
- Whole hours, or 0. Decimals work too: 1.5 hours is added as 90 minutes.
- Minutes
- Minutes. Values of 60 or more are carried into hours, so 135 minutes becomes 2 h 15 m.
- Seconds
- Seconds, fractions included for race splits.
Duration formula
total seconds = hours × 3,600 + minutes × 60 + seconds · decimal hours = total seconds ÷ 3,600
Everything is turned into seconds — an hour is 3,600 and a minute 60 — and added up. That total is then shown back as a tidy hours-minutes-seconds figure, so 90 minutes becomes 1 hour 30 minutes, and as decimal hours, the form timesheets and pay calculations use: 1 hour 30 minutes is 1.5 hours, not 1.30. The page also gives the total in minutes and in seconds, and breaks long totals into days and hours. Because each box is added on its own, the boxes do not need to be 'tidy' first: 0 hours, 135 minutes and 90 seconds is a valid entry and comes out as 2 hours 16 minutes 30 seconds. That makes the page a quick way to add up several durations — put the total of each unit in its box — or to turn a stopwatch reading into decimal hours.
Duration worked example
1 hour 30 minutes is 1 × 3,600 + 30 × 60 = 5,400 seconds: 90 minutes, or 1.5 decimal hours. Entering 0 hours and 90 minutes gives the same answer, carried into 1 h 30 m.
More Duration examples
135 minutes on their own: 8,100 seconds, shown as 2h 15m 0s, or 2.25 decimal hours.
A marathon finish of 3:59:30: 14,370 seconds, which the page writes as 3h 59m 30s and 3.9917 decimal hours — half a minute inside four hours.
Where the Duration calculator can give the wrong answer
- Decimal hours are not clock notation. 7 hours 45 minutes is 7.75 hours; 7.45 would be 7 hours 27 minutes.
- Negative values are not accepted; use the hours calculator for the time between two clock times.
- Seconds can be fractional, for race splits; the result keeps them to the millisecond.
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Duration reference table
| Minutes | Decimal hours |
|---|---|
| 5 | 0.083 |
| 6 | 0.1 |
| 10 | 0.167 |
| 12 | 0.2 |
| 15 | 0.25 |
| 20 | 0.333 |
| 30 | 0.5 |
| 40 | 0.667 |
| 45 | 0.75 |
| 50 | 0.833 |
Duration FAQ
- Divide the minutes by 60 and add them to the hours. 2 hours 20 minutes is 2 + 20 ÷ 60 = 2.333 hours.
- 150: 2.5 × 60.
- Yes. 135 minutes is carried into 2 h 15 m.
- 1 hour 45 minutes: 0.75 × 60 = 45.
- Multiply the decimal part by 60. 3.9917 hours is 3 hours plus 0.9917 × 60 = 59.5 minutes — 3 h 59 m 30 s.
- Add each unit and carry: 1 h 50 m + 2 h 25 m = 3 h 75 m = 4 h 15 m. Or type the sums straight in — 3 hours and 75 minutes — and the page does the carrying.
- 6 minutes, since 0.1 × 60 = 6. Timesheets that round to tenths of an hour are rounding to 6-minute blocks.
- 86,400: 24 × 3,600. A week is 604,800 seconds.