Time duration calculator
Find the hours and minutes between a start and end time, subtract a break, and get the decimal hours used on timesheets.
Clock arithmetic only; daylight-saving and payroll rounding rules are not applied.
How this calculator works
Time duration is the difference between two clock times, expressed in hours and minutes. When the end time is earlier than the start time, the shift has crossed midnight, so the calculator adds 24 hours — a 22:00 to 06:00 shift is 8 hours, not a negative number. Breaks are subtracted afterwards, because an unpaid break is time at work that does not count as paid hours.
Timesheets usually need decimal hours rather than hours and minutes: 7 hours 45 minutes is 7.75 decimal hours. The decimal figure is what payroll systems multiply by the hourly rate, so getting the conversion right matters — 45 minutes is 0.75 of an hour, not 0.45. If you are paid for an overnight shift, check whether your employer uses a different midnight-crossing convention, and remember that daylight-saving changes can add or remove an hour twice a year.
The formula
Convert each time to minutes after midnight, subtract, add 24 hours if the end is earlier, then remove the break:
start = hh × 60 + mm
end = hh × 60 + mm (if end ≤ start: end += 1440)
minutes = end − start − break
decimal hours = minutes / 60To go the other way, multiply decimal hours by 60 to get minutes: 2.25 hours = 135 minutes.
Worked example
From 09:15 to 17:45 with a 30-minute break is 8 hours 0 minutes — 8.0 decimal hours, or 480 paid minutes.
Common mistakes
- Reading minutes as decimals. 30 minutes is 0.5 hours, not 0.30. Convert by dividing minutes by 60.
- Forgetting the overnight case. An end time before the start time means the next day; otherwise the difference is negative.
- Subtracting breaks twice. If the shift length already excludes the break, set the break field to 0.
Frequently asked questions
How do I calculate hours worked?
Subtract the start time from the end time, add 24 hours if the shift crossed midnight, then subtract unpaid breaks. Divide minutes by 60 for decimal hours.
What is 7 hours 45 minutes in decimal?
7.75 hours: 45 ÷ 60 = 0.75. Payroll systems multiply the decimal figure by the hourly rate.
Does a 30-minute break get deducted?
Only if it is unpaid. Paid breaks are part of working time and should not be subtracted.
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