How to calculate hours worked
To total a timesheet you subtract start from end, take off unpaid breaks, and convert to decimal hours for pay. This guide shows each step with examples, including night shifts that cross midnight and the conversion mistake that costs people money.
The short version
- Subtract the start time from the end time. 17:30 − 09:00 = 8 h 30 m.
- Subtract unpaid breaks. A 30-minute break leaves 8 h 00 m.
- Add up the days. Add hours and minutes separately, carrying 60 minutes into an hour.
- Convert to decimal hours if payroll needs it, then multiply by the hourly rate.
Skip the arithmetic. The free Hours Calculator does this for you, shows the formula and the working with your own numbers, and runs in your browser - nothing you type is uploaded. Also useful: Percentage Calculator, Age Calculator.
A worked week
| Day | Start – end | Break | Hours |
|---|---|---|---|
| Mon to Thu (each) | 09:00 – 17:30 | 30 min | 8 h 00 m |
| Friday | 09:00 – 15:15 | 15 min | 6 h 00 m |
| Week | 38 h 00 m |
Minutes are not decimals
Clocks use base 60 and payroll uses base 10. 7 hours 45 minutes is 7.75 hours, not 7.45. To convert, divide the minutes by 60: 45 ÷ 60 = 0.75. Mixing them up is the most common timesheet mistake - at 15 per hour, 7.45 instead of 7.75 loses 4.50 for the day.
| Minutes | Decimal | Minutes | Decimal |
|---|---|---|---|
| 15 | 0.25 | 40 | 0.67 |
| 20 | 0.33 | 45 | 0.75 |
| 30 | 0.50 | 50 | 0.83 |
Night shifts that cross midnight
If the end time is earlier than the start time, the shift ends the next day: add 24 hours to the end time. A shift from 22:00 to 06:00 is (06:00 + 24:00) − 22:00 = 8 hours. A shift cannot be longer than 24 hours without a date, so check any result near that.
Add the minutes first, then convert
Add the hours and minutes of the whole week, then convert once. Rounding each day to two decimals before adding can drift the total by a few minutes over a month.
What this does not cover
Overtime thresholds, rounding rules, paid breaks, tax and deductions depend on your country, contract and employer. Use the total hours here as the input to those rules, and check them with your payroll or labour regulations.