How to Calculate the Duration Between Two Times
Subtracting times looks simple until a period crosses midnight. Here is the reliable way to work out any duration.
What is the Time Duration Calculator?
Enter a start time and an end time in hours and minutes and the calculator finds the difference. If the end time is earlier than the start time it assumes the period runs overnight and adds 24 hours, so a shift from evening to morning still comes out right.
How to use it
- Enter the start time as hours and minutes.
- Enter the end time as hours and minutes.
- Press Calculate to see the duration in hours and minutes.
Worked example
From 22:30 to 06:45 the tool gives: 8 hours 15 minutes (495 minutes total).
How long is it from 22:30 to 06:45 the next morning?
It is 8 hours and 15 minutes, or 495 minutes in total. Because the end time is earlier in the day than the start time, you add 24 hours to the end time first, then subtract. That overnight rule is the key step most people miss.
Frequently asked questions
How do overnight periods work?
If the end time is earlier than the start time, 24 hours are added to the end time before subtracting, so 22:30 to 06:45 gives 8 hours 15 minutes.
What time format should I use?
Use 24-hour hours (0 to 23) and minutes (0 to 59) for both times.