Time Calculator
Add and subtract durations in hours, minutes and seconds.
Total
2:15:30
- Decimal hours
- 2.2583
- Total minutes
- 135.5
- Total seconds
- 8,130
Adding 2 hours 45 minutes to 1 hour 30 minutes is awkward in your head because minutes roll over at 60, not 100. This calculator lets you list any number of durations, mark each as added or subtracted, and see a correct total.
It works with hours, minutes and seconds and shows the answer as h:mm:ss, in decimal hours and in total minutes.
How time calculator works
Each row is one duration. Enter hours, minutes and seconds, and choose plus or minus. The tool converts every row to seconds, adds or subtracts them and converts the total back, carrying 60 seconds into a minute and 60 minutes into an hour.
If the total goes below zero it shows a negative duration, which makes it easy to see when you have overspent a time budget.
The formula
Total seconds = Σ ± (hours × 3600 + minutes × 60 + seconds)
h:mm:ss = carry 60 s into minutes and 60 min into hoursWorked example: two tasks and a break
Add 2:30:00 and 1:45:00 to get 4:15:00.
Subtract a 0:20:00 break to get 3:55:00.
In decimal hours that is 3.92.
When to use this tool
- Adding lap or split times, or the running time of several videos.
- Totalling time spent on tasks for a client or a report.
- Subtracting breaks from a block of time.
- Planning a schedule that has to fit inside a fixed window.
Common mistakes to avoid
- Treating minutes as decimals, so 1:30 becomes 1.30. Half an hour is 0.5 of an hour.
- Forgetting to carry: 45 + 30 minutes is 1 hour 15 minutes, not 75 minutes written as 0:75.
- Mixing durations with clock times. To find the gap between two clock times use the hours calculator.
Frequently asked questions
- How do I add hours and minutes?
- Add the hours together, add the minutes together, then convert every full 60 minutes into an hour. Or list each duration in the calculator.
- How do I subtract time?
- Convert both durations to minutes or seconds, subtract, then convert back. Mark a row as minus in the calculator to do the same.
- How do I convert h:mm to decimal hours?
- Divide the minutes by 60 and add to the hours: 3:55 is 3 + 55 ÷ 60 = 3.92 hours.
- What is the difference between this and the hours calculator?
- This tool adds and subtracts durations. The hours calculator finds the gap between a start and an end clock time.
Learn more
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Results are for information only and are not financial, legal or medical advice. The calculation logic is covered by automated tests, and examples on this page are worked out and re-checked before publishing. Spotted a mistake? Tell us.