Calculators & everyday math
How to Subtract Time Durations
Subtracting one length of time from another — a break from a shift, time used from time available — needs borrowing in base 60. This guide shows the method, a timesheet example, and what a result below zero means.
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Subtract, borrowing 60 when needed
- Subtract the minutes. If the top minutes are smaller, borrow 1 hour as 60 minutes: 5h 0m becomes 4h 60m.
- Now subtract: 60 − 35 = 25 minutes, and 4 − 1 = 3 hours.
- So 5h 0m − 1h 35m = 3h 25m.
With seconds
Borrow a minute as 60 seconds the same way: 5h 0m 0s − 1h 35m 30s is 3h 24m 30s.
A timesheet example
A shift from 8:45 AM to 5:15 PM is 8 hours 30 minutes. Taking off a 45-minute unpaid break leaves 7 hours 45 minutes, or 7.75 decimal hours.
When the result is negative
If the second duration is longer, the answer is negative: 1h − 2h 30m is −1h 30m. It means the second length of time is longer by 1 hour 30 minutes — for example, a task that ran 1 hour 30 minutes over a 1-hour estimate.
Subtract Durations FAQ
- How do I subtract hours and minutes?
- Subtract the minutes, borrowing 60 from the hours if needed, then subtract the hours.
- What is 5 hours minus 1 hour 35 minutes?
- 3 hours 25 minutes.
- How do I take a lunch break off the hours worked?
- Work out the total span first, then subtract the break as a duration.
- What does a negative result mean?
- The duration you subtracted was longer than the one you started with.
- Can I subtract clock times the same way?
- For clock times, use the Hours Between Times Calculator, which also handles spans that cross midnight.
Related guides
- Add Hours and MinutesAdd lengths of time by hand with carrying, total a list of durations, and add times in a spreadsheet without the total wrapping past 24 hours.
- Hours, Minutes, SecondsConvert durations between hours, minutes, and seconds, split a number of seconds into hours, minutes, and seconds, and turn decimal hours into minutes.
Open the tool
Jump into Time Duration Calculator when you are ready to process your files.
