How to calculate hours worked in a week

Updated November 14, 2026 · Worked examples use whole minutes

Subtract the start time from the finish time for each shift, deduct unpaid breaks, then add the shifts together. Keep everything in hours and minutes and convert to decimal hours only once, at the end of the week.

Calculate it step by step

1. Write the start and finish of each shift on a 24-hour clock.
2. Subtract the start from the finish. If the shift ended after midnight, add 24 hours to the finish first.
3. Deduct the unpaid break minutes from that shift.
4. Add all shifts as hours and minutes. Every 60 minutes carries over as one hour.
5. If you need decimal hours, divide the leftover minutes by 60 and add them to the whole hours.

Worked example

Monday to Friday, 8:30 am to 5:00 pm, with a 30-minute unpaid lunch: each day spans 8 hours 30 minutes and leaves 8 hours. Five days make 40 hours, or 40.00 decimal hours. If Friday ends at 4:15 pm, that day is 7 hours 15 minutes and the week is 39 hours 15 minutes, or 39.25 hours.

Check your own shifts in the time card calculator

How do you subtract times and which breaks come off?

Writing times on a 24-hour clock makes afternoon times easy to subtract. 5:30 pm becomes 17:30, so a shift from 8:15 to 17:30 lasts 9 hours 15 minutes before breaks. When the finish minutes are smaller than the start minutes, borrow an hour: 16:10 − 8:45 becomes 15:70 − 8:45, which is 7 hours 25 minutes.

Only deduct breaks your employer does not pay for. Paid rest breaks stay in the total. If you are not sure which breaks are paid, check your contract, staff handbook or the timekeeping record your workplace uses.

Further reading

• US Department of Labor Fact Sheet 22: hours worked under the FLSA
• GOV.UK guide to rest breaks at work