Time Duration Calculator
Calculate the duration between a start time and end time in hours and minutes, with support for overnight periods. Great for timesheets and shifts. Free, private.
Last reviewed by the Radiatus Cloud team
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Calculate the duration between times
Working out exactly how long there is between two clock times, particularly when the period runs across midnight, is genuinely fiddly to do reliably in your head. This calculator computes the duration between a start time and an end time in hours and minutes, so you get the elapsed time instantly without wrestling with the awkward arithmetic yourself.
Why time arithmetic trips people up
Subtracting clock times is deceptively awkward for two reasons: minutes and hours are counted in base 60 rather than the base 10 we are used to, and a period that crosses midnight, say from 10pm to 6am, produces a wrong or even negative answer if you simply subtract the clock numbers naively. This is exactly the calculation needed for filling in timesheets, working out shift lengths, and finding durations of all kinds, and doing it by hand quietly invites mistakes. The calculator handles both the base-60 arithmetic and the midnight crossing correctly, giving you the true duration in hours and minutes every time.
A calculation, not advice
It runs entirely in your browser, so nothing you enter is uploaded and it works without an account, keeping everything on your own machine and available on any device immediately.
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Frequently Asked Questions
Why is subtracting times tricky?
Because minutes and hours are base 60, not base 10, and a period crossing midnight gives a wrong or negative result if subtracted naively.
Does it handle times crossing midnight?
Yes. It correctly computes a duration where the end time is on the next day, such as an overnight shift.
What is it useful for?
Timesheets, shift lengths, and any time you need the elapsed hours and minutes between two clock times.
What format is the result?
Hours and minutes, the natural way to express a duration between two times.
Is my data uploaded?
No. The calculation runs entirely in your browser.
Privacy & Security
All processing happens locally in your browser — nothing is uploaded.
How to Use
Enter a start and end time; the duration is calculated, handling overnight spans.
Disclaimer: This tool is provided "as is" without warranty of any kind. Results are for educational and utility purposes.
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