Finding hours worked sounds simple until a shift crosses noon, a lunch break appears or the clock rolls past midnight. The method below works every time, by hand or with a calculator, and it shows where most mistakes come from.
The four-step method
- Write both times on a 24-hour clock. 8:15 AM is 08:15 and 4:45 PM is 16:45. This removes AM and PM errors.
- Subtract the start from the end. 16:45 minus 08:15 is 8 hours 30 minutes. If the end minutes are smaller than the start minutes, borrow an hour. For 16:20 minus 07:50, take 7 hours off 16:20 to get 9:20, then take off the 50 minutes to get 8:30.
- Subtract unpaid breaks. Only breaks where you are completely off duty come out. A 30-minute unpaid lunch leaves 8:00.
- Convert to decimal hours if you need to multiply by a rate. 8 hours 30 minutes is 8.5. See how to convert minutes to decimal hours.
Hours worked = (end time - start time) - unpaid break
Overnight shifts
If the end time is earlier than the start time, the shift ended the next day. Add 24 hours to the end time before subtracting. A shift from 22:30 to 07:00 becomes 22:30 to 31:00, which is 8 hours 30 minutes. With a 30-minute break that is 8:00.
If the start and end are the same clock time, the shift is either zero or exactly 24 hours. A calculator cannot know which, so record the dates when a shift could be that long.
A full week, worked out
| Day | In | Out | Unpaid break | Hours worked |
|---|---|---|---|---|
| Monday | 8:15 AM | 4:45 PM | 30 min | 8:00 |
| Tuesday | 7:50 AM | 4:20 PM | 30 min | 8:00 |
| Wednesday | 9:00 AM | 5:15 PM | 45 min | 7:30 |
| Thursday | 8:00 AM | 12:00 PM | none | 4:00 |
| Friday | 8:30 AM | 5:00 PM | 30 min | 8:00 |
| Week total | 35:30 (35.50 hours) |
Add the minutes first: 0 + 0 + 30 + 0 + 0 = 30 minutes. Then add the hours: 8 + 8 + 7 + 4 + 8 = 35. The total is 35 hours 30 minutes. The time card calculator produces the same totals from the punches.
Mistakes that cause wrong totals
- Typing 7.45 for 7 hours 45 minutes. On a time clock it reads as 7:45, but as a decimal it means 7 hours 27 minutes.
- Deducting paid breaks. Short rest breaks of roughly 5 to 20 minutes are normally paid time and should stay in your hours.
- Forgetting that a day has 24 hours. 12:00 AM to 12:00 PM is 12 hours, not 0.
- Rounding every punch in the employer's favor. Federal rules allow rounding only when it averages out over time.
Hours worked and hours paid are not always the same. Travel time, on-call time and training time follow separate rules. Use the result as a starting point and check your employer policy or the Department of Labor guidance.