Time Duration Calculator
Find the duration between two times, or add and subtract hours and minutes. Times past midnight are handled automatically - great for work estimates.
Inputs are not collected. Usage measurement requires your consent.
Duration
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Total (minutes)
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If the end time is earlier than the start time, it is treated as the next day.
Done
Time Duration Calculator
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How to use
- 1
Pick a mode
Choose the duration tab or the add/subtract tab.
- 2
Enter the times
Fill in the start and end times, or the base time and the hours/minutes to shift.
- 3
Read the result
The duration or the resulting time appears instantly.
Features
- Instant duration between two times, in hours and minutes
- Automatic handling of times past midnight
- A mode to add or subtract hours and minutes from a base time
- Everything computed in your browser; nothing is transmitted
Use cases
Measuring study or work sessions
Sum the actual time spent from start and end clock times.
Travel and cooking times
Check how long a trip or a recipe took from clock times.
Finding when a meeting ends
Work out the end time from a start time and a length.
Details
A duration is the end time minus the start time: 9:15 to 12:45 is 3 hours 30 minutes. When the end time is earlier than the start time — say 22:00 to 05:00 — it is treated as the next day by adding 24 hours first. Forgetting this midnight wrap-around is the most common mistake in duration math.
To shift a time, convert everything to minutes, add or subtract, and take the remainder when divided by 1440 (24 hours × 60 minutes). Adding 2 hours 45 minutes to 14:30 gives 870 + 165 = 1,035 minutes, which converts back to 17:15. If a subtraction goes negative, the remainder is normalized so the result lands on the previous day.
This tool does not account for breaks, night-shift premiums or any labor-law treatment — use it for estimates only. For multi-day spans, combine it with the date calculator.
FAQ
Can it handle times that cross midnight?
Yes. When the end time is earlier than the start time, it is treated as the next day — 22:00 to 05:00 is 7 hours.
Can I use it for work-hours calculation?
You can find durations, but breaks, night premiums and other labor-rule treatments are not included. Treat the results as estimates.
Does it support seconds?
Hours and minutes only. For second precision, use the stopwatch tool on this site.
Are the times I enter sent anywhere?
No. All computation happens locally in your browser and nothing you enter is transmitted.
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All processing happens in your browser. Your files are never uploaded.
Verified: Durations, midnight wrap-around, add/subtract and error states are covered by browser tests
Did you know?
For durations past midnight, add 24 hours before subtracting: 22:00 to 05:00 works out to 7 hours that way.