Time Duration Calculator
Add and subtract multiple time durations with automatic overflow normalization.
Time duration
Updates as you typeMode
What do you want to calculate? ?
Durations
Quick presets
Rows ?
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Times
Start time
End time
If end is earlier than start ?
Date-times
Start
End
Examples
How It Works
The time duration calculator adds and subtracts multiple time spans and normalizes the result. For example, 1h 45m + 0h 30m = 2h 15m, and 90 minutes is automatically normalized to 1h 30m.
You can add up to 10 duration rows. The first row is always added; subsequent rows can be set to add (+) or subtract (−). The total is converted to seconds first, then normalized into hours, minutes, and seconds.
Overflow handling: 75 seconds becomes 1 minute 15 seconds, and 90 minutes becomes 1 hour 30 minutes. If the result is negative (subtracting more than was added), a minus sign is shown.
You can add up to 10 duration rows. The first row is always added; subsequent rows can be set to add (+) or subtract (−). The total is converted to seconds first, then normalized into hours, minutes, and seconds.
Overflow handling: 75 seconds becomes 1 minute 15 seconds, and 90 minutes becomes 1 hour 30 minutes. If the result is negative (subtracting more than was added), a minus sign is shown.
Tips & Best Practices
Enter large values in any field — 90 minutes is fine, the calculator normalizes it to 1h 30m.
Use subtract to deduct break times from total work hours.
Frequently Asked Questions
Can the result be negative?
Yes — if you subtract more than you add, the result shows a minus sign. For example, 1 hour minus 2 hours = −1h 0m 0s.
How many durations can I add?
Up to 10 duration rows. Click 'Add Duration' to add more rows, and each can be set to add or subtract.