Time Duration Calculator
Hours and minutes between a start and end time.
Input sheet
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From timing a shift to figuring out how long a flight or meeting actually ran, finding the gap between two clock times is something people do constantly and get wrong surprisingly often, especially when the end time falls after midnight.
How it works
Converts both times to minutes and subtracts; an end before the start rolls over to the next day.
Both times are converted to a count of minutes since midnight and subtracted. If the end time is earlier than the start time, the calculator assumes you crossed midnight and adds 24 hours, so an 11:00 PM start and 2:00 AM end correctly reads as 3 hours.
Results are shown three ways: as hours and minutes, as a total minute count, and as decimal hours. Decimal hours are what payroll and billing systems usually want, where 90 minutes is 1.50 hours rather than 1.30.
Duration in minutes = (end hour × 60 + end minute) − (start hour × 60 + start minute); add 1440 minutes if that result is negative. Decimal hours = minutes ÷ 60.
Worked examples
Start 9:30, end 17:15. → 7 hr 45 min (465 minutes, 7.75 decimal hours)
17:15 is 1035 minutes after midnight and 9:30 is 570, a difference of 465 minutes.
Start 22:00, end 06:00. → 8 hr 0 min, crossing midnight
Because the end is earlier than the start, 24 hours are added, giving an 8-hour overnight span.
Tips & gotchas
- Enter times in 24-hour format: 5:15 PM is hour 17, minute 15.
- Use the decimal-hours figure for timesheets and invoices, since most payroll software expects hours as a decimal.
- An end time earlier than the start is treated as the next day, which is exactly what you want for overnight shifts.
- This counts the raw gap; subtract any unpaid breaks separately, or use the Hours Worked calculator which handles breaks and pay.
FAQ
What happens if the end time is before the start time?
The calculator assumes the period crosses midnight and adds 24 hours, so an overnight span is measured correctly.
Why does it show decimal hours?
Decimal hours (where 30 minutes is 0.50) are the format payroll and billing systems use. The calculator converts the duration automatically.
Does this subtract breaks?
No. It measures the full gap between the two times. For paid hours after an unpaid break, use the Hours Worked calculator.
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