Calculating work hours looks easy when a day starts at 9:00 and ends at 17:00. It becomes more error-prone when you need to subtract lunch breaks, combine schedules or handle a shift ending after midnight.
The reliable method is to separate three values: start time, end time and total unpaid breaks. Actual working time is the elapsed duration minus the breaks that should not count as work.
The basic formula
For a day that does not cross midnight:
working time = end time - start time - breaks
Example: start at 8:30, finish at 17:15 and take a 45-minute break. The elapsed time is 8 h 45 min; after subtracting the break, the result is 8 hours.
7 h 30 does not mean 7.30 hours
Thirty minutes is half an hour, so 7 h 30 = 7.5 hours. Likewise, 15 minutes = 0.25 hour and 45 minutes = 0.75 hour. This matters when adding durations in spreadsheets or reports. Bethemesh’s duration converter can convert minutes to hours and back.
Subtracting breaks correctly
Only subtract a break when it is not counted as working time. A 9:00–18:00 presence period with a one-hour break represents 8 working hours. If there are several breaks, add them first and subtract their total.
The work hours calculator accepts a start time, end time and break duration directly.
What if the shift crosses midnight?
A shift from 22:00 to 06:00 is not negative: it lasts 8 hours. With a 30-minute break, actual working time is 7 h 30 min. A suitable calculator must treat an earlier end time as potentially belonging to the following day.