Time Duration Calculator

Find the exact duration between two clock times, or add/subtract time from a given time.

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Duration Between Two Times
About Time Duration Calculations

This calculator works with clock times (hours, minutes and seconds) rather than calendar dates. It's handy for working out shift lengths, cooking or workout timings, meeting durations, or any calculation based on the time of day.

Common uses
  • Calculating the length of a work shift, including overnight shifts
  • Working out how long a journey, call or meeting lasted
  • Adding a cooking or processing time to a start time
  • Splitting a total duration into hours, minutes and seconds

Looking for the number of days, weeks or months between two calendar dates instead? Try the Date Difference Calculator.

Frequently Asked Questions

Enter a start time and an end time in the "Duration Between Times" tab and the calculator works out the exact difference in hours, minutes and seconds. If the end time is earlier than the start time, tick "ends the next day" to calculate an overnight duration, such as a night shift.

Switch to the "Add / Subtract Time" tab, enter a starting time, choose how many hours, minutes and seconds to add or subtract, and the calculator returns the resulting clock time. If the result crosses midnight, it shows whether that falls on the next or previous day.

No. The Date Difference Calculator works out the number of days, weeks, months or years between two calendar dates. This tool works out the duration between two times of day (hours, minutes, seconds), which is useful for shift lengths, cooking times, workout splits, or any clock-based calculation.

If your end time is earlier in the day than your start time (for example, starting at 22:00 and finishing at 06:00), tick the "ends the next day" checkbox so the calculator adds 24 hours to the end time before working out the duration.
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