How to calculate hours between two times
Convert both times to minutes after midnight, subtract the start from the end, and add 24 hours (1,440 minutes) if the shift ends on the next day. Then subtract the unpaid break. The calculator does exactly this, in whole minutes, so nothing is lost to rounding until you choose how to display the result.
Day shift. 09:00 to 17:30 on the same day is 8 h 30 min (510 minutes). Minus a 30-minute break, that is 8 h 00 min, or 8.00 decimal hours.
Overnight shift. 22:00 to 06:00 the next day is 8 h 00 min (480 minutes): 2 hours before midnight and 6 after. Minus a 30-minute break, that is 7 h 30 min, or 7.50 decimal hours.
Converting hours and minutes to decimal hours
Payroll and invoicing tools usually want decimal hours: divide the minutes by 60. A common mistake is to type 7 h 45 min as 7.45. The correct value is 7.75, because 45 minutes is three quarters of an hour.
| Minutes | Decimal hours | Minutes | Decimal hours |
|---|---|---|---|
| 5 | 0.0833 | 35 | 0.5833 |
| 10 | 0.1667 | 40 | 0.6667 |
| 15 | 0.25 | 45 | 0.75 |
| 20 | 0.3333 | 50 | 0.8333 |
| 25 | 0.4167 | 55 | 0.9167 |
| 30 | 0.50 | 60 | 1.00 |
Repeating decimals such as 0.1667 are rounded. The calculator copies four decimals so that a week of shifts adds up to within a fraction of a minute; if your employer has its own rounding rule (for example to the nearest quarter hour), apply it to the total minutes.
Common shift lengths
| Shift | Unpaid break | Hours worked | Decimal |
|---|---|---|---|
| 09:00 – 17:00 | 30 min | 7 h 30 min | 7.50 |
| 08:00 – 16:30 | 30 min | 8 h 00 min | 8.00 |
| 06:00 – 14:30 | 30 min | 8 h 00 min | 8.00 |
| 15:00 – 23:30 | 30 min | 8 h 00 min | 8.00 |
| 07:00 – 19:00 | 60 min | 11 h 00 min | 11.00 |
| 19:00 – 07:00 (next day) | 60 min | 11 h 00 min | 11.00 |
| 22:00 – 06:00 (next day) | 30 min | 7 h 30 min | 7.50 |
Adding up a week
Add the minutes first and convert once at the end. Five shifts of 7 h 45 min are 5 × 465 = 2,325 minutes, which is 38.75 hours. Adding the mistaken 7.45 five times gives 37.25, an hour and a half short. If you add rounded decimals instead (for example 0.1667 for every 10 minutes), the total drifts slightly over many entries, which is why the calculator shows total minutes alongside decimal hours.
FAQ
How do I calculate hours for a shift that goes past midnight?
Choose "Next day" as the end day. The calculator adds 24 hours to the end time before subtracting, so 22:00 to 06:00 counts as 8 hours instead of an error.
What if the start and end times are the same?
On the same day the duration is zero. With "Next day" it is a full 24 hours. The calculator never assumes 24 hours for you.
Why is 7 hours 45 minutes 7.75 and not 7.45?
Because an hour has 60 minutes, not 100. 45 ÷ 60 = 0.75, so 7 h 45 min = 7.75 hours. Entering 7.45 would underpay or under-bill 18 minutes.
Does it handle daylight saving time?
No. It measures clock time on the wall. On the night clocks go forward or back, a shift crossing the change lasts one hour less or more than the clock difference shows, so adjust that shift by hand.
This tool does not apply break rules, overtime or pay law. Check your contract or local labour rules for which breaks are paid.