MTMasterTool

Time Duration Calculator

Calculate time duration with calendar-date arithmetic.

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What this tool does

Calculate time duration with calendar-date arithmetic. An earlier end time means overnight; equal times mean zero duration, not 24 hours.

How to use the Time Duration Calculator

  1. Enter or select start time (hh:mm).
  2. Enter or select end time (hh:mm).
  3. Read the calculated result; change any measurement to compare alternatives.

Formula

elapsed minutes=(end−start+1440)%1440; hours=minutes/60
start
Start time (HH:MM)
end
End time (HH:MM)

An earlier end time means overnight; equal times mean zero duration, not 24 hours.

Worked example

For time duration calculator, the following measurements illustrate the exact method: Start time (HH:MM): 09:00; End time (HH:MM): 17:30.

Inputs

  • Start time (HH:MM)09:00
  • End time (HH:MM)17:30

Result

  • Duration (hours)8.5
  • Hours and minutes8h 30m

Results explained

Duration (hours)
Duration (hours) from the formula above. An earlier end time means overnight; equal times mean zero duration, not 24 hours.
Hours and minutes
Hours and minutes from the formula above. An earlier end time means overnight; equal times mean zero duration, not 24 hours.

Frequently asked questions

elapsed minutes=(end−start+1440)%1440; hours=minutes/60

An earlier end time means overnight; equal times mean zero duration, not 24 hours.

Yes. Valid calendar dates use Gregorian leap-year rules.

Date-only calculations use UTC calendar days to avoid daylight-saving shifts. Clock-time durations use the provided elapsed clock times, not a timezone database.

Check the date format, direction, whether endpoints are included, and whether holidays need to be excluded.