How to Calculate Hours Worked and Overtime

ficklestudio26 · Facts checked October 25, 2026

Timesheets ask for decimal hours, but clocks show minutes. Here is how to convert between them, and what the US federal rules say about overtime and rounding.

Open the hours calculator
Enter start and end times, subtract breaks, and read the total.
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Step 1: subtract the start from the end

Hours worked = end time − start time − unpaid break. A shift from 8:30 to 17:15 with a 30-minute unpaid lunch is 8 hours 45 minutes, minus 30 minutes, which is 8 hours 15 minutes. If the shift crosses midnight, add 24 hours to the end time before subtracting.

Step 2: convert minutes to decimal hours

Divide the minutes by 60. This is plain arithmetic, so you can check any result yourself.

15 minutes = 0.25 hour
30 minutes = 0.5 hour
45 minutes = 0.75 hour
10 minutes = 0.1667 hour (the decimal repeats, so payroll systems round it)

So 8 hours 15 minutes is 8.25 hours. A common mistake is to write 8.15, which would mean 8 hours 9 minutes.

Overtime under US federal law

The Fair Labor Standards Act (FLSA) requires covered, non-exempt employees to be paid at least one and one-half times their regular rate for hours worked over 40 in a workweek. The workweek is a fixed, recurring period of 168 hours (seven consecutive 24-hour periods), and each week stands alone: you cannot average two weeks together. Some states have extra rules, such as daily overtime, and some employees are exempt, so a result here is a guide and not payroll advice.

Example, using our own arithmetic: with a regular rate of $20 an hour and 44 hours worked in one week, the pay is 40 × $20 + 4 × $20 × 1.5 = $800 + $120 = $920, ignoring any other pay that would change the regular rate.

Rounding punched time

The federal regulation on recording working time says that rounding to the nearest five minutes, one-tenth of an hour or quarter of an hour is acceptable, provided the practice averages out so that employees are fully paid for all the time they actually work. Rounding that always favors the employer does not meet that test. If you track your own hours, keep the exact minutes and round only once, at the end.

A quick checklist

Write the exact start and end times.
Subtract unpaid breaks only.
Convert minutes by dividing by 60.
Add the days of one workweek, then compare with 40.