About the Time Duration Calculator
This works out how long is between two clock times, or adds and subtracts time durations. It's the quick answer for how many hours you worked between clock-in and clock-out, how long an activity or shift lasts, total up several durations, or subtract a break from a total. Two modes cover the common needs: the gap between two times, and arithmetic on durations.
How it works
Between two times: it converts each time to seconds since midnight and subtracts. If the end is earlier than the start (or you tick "next day"), it adds 24 hours so an overnight span — like a 22:00 to 06:00 shift — comes out as 8 hours rather than negative.
Add / subtract durations: it converts each hours-minutes-seconds duration to seconds, adds or subtracts, and formats the result. Every answer is also shown as a decimal number of hours, total minutes and total seconds.
Assumptions and behaviour
- "Between two times" works with clock times to the second; an overnight gap is handled by the next-day option or automatically when the end is earlier.
- Duration arithmetic accepts hours, minutes and seconds in each duration.
- Results are shown both as
Hh Mm Ssand as decimal hours, minutes and seconds for payroll or logging. - Subtraction can produce a negative duration, shown with a minus sign.
Limitations
- The "between two times" mode works with times of day within a single 24-hour span (with the next-day option for overnight). For a gap spanning multiple days, use the Date Difference Calculator.
- It doesn't apply time zones or daylight-saving — it's plain clock arithmetic.
- It works to the second; it doesn't handle fractions of a second.
- For decimal payroll, note it rounds the displayed decimal hours to two places.
Privacy
The calculation runs entirely in your browser. Nothing is uploaded or stored.
Get FreeMyTask as an app