Time calculator
Add and subtract hours, minutes and seconds, or add time to a clock time.
About this calculator
This time calculator adds and subtracts time. Type a list of durations, one per line, to get the total in hours, minutes and seconds, or start from a clock time and add or take away hours and minutes.
It's handy for timesheets, recipes, video edits, workouts and travel plans.
How it works
Each line is turned into seconds, added up (lines starting with a minus are taken away) and shown again as hours, minutes and seconds. A plain number counts as minutes.
Last reviewed:
Worked example
- Work out: Add up durations
- One duration per line, such as 1:30, 2h 15m or -45m: 1:45; 2h 30m; -20m; 45s
Total: 3 h 55 min 45 s
Common questions
How do I add hours and minutes?
Add the minutes together, and for every 60 minutes carry 1 hour. For example, 1:45 plus 2:30 is 3 hours 75 minutes, which is 4 hours 15 minutes.
How do I convert minutes to decimal hours?
Divide the minutes by 60. So 45 minutes is 0.75 hours and 1 hour 30 minutes is 1.5 hours. The calculator shows the total in decimal hours too.
What happens if the time goes past midnight?
In clock mode, the calculator tells you if the finishing time falls on the next day, or on the day before when you subtract.
The story behind it
Where the idea came from: We count time in 60s because of the Babylonians, who did their arithmetic in base 60.
Sixty divides evenly by 2, 3, 4, 5, 6, 10, 12, 15, 20 and 30, which made it ideal for sharing things out without fractions. Babylonian astronomers used it, Greek astronomers inherited it, and hours were later split into 60 minutes of 60 seconds. That is why adding up time still needs a little care.
Why you can trust this calculator
- It runs in your browser. Nothing you type into it is sent anywhere.
- The method is explained on this page, so you can check it yourself.
- Free to use, with no sign-up.
- Results are estimates, so please double-check anything important.
- Spotted a mistake? Tell us and we'll look into it.
After 15 years as a mathematics educator, I built CalculStore to give students, teachers, professionals and anyone working with numbers simple, reliable tools.
Meet the founder