About this calculator
Use this hours calculator to find how long you worked between a start and end time (with a break taken off), or to add up several lengths of time such as 7:45 and 1h 30m.
It shows the answer as hours and minutes and as decimal hours, which is the form invoices and payroll systems usually want. Add an hourly rate to see the pay.
Worked examples
Real numbers, worked out by the same calculator. Press “Use these numbers” to try one above.
9:00 to 17:30 with a 30 minute break
- Time worked
- 8h
- In decimal hours
- 8
From 09:00 to 17:30, less a 30 minute break, is 8h (8 hours).
9am to 5:45pm at £20 an hour
- Time worked
- 8h 45m
- In decimal hours
- 8.75
- Pay at that rate
- £175.00
From 9am to 5:45pm is 8h 45m (8.75 hours). At £20.00 an hour that's £175.00.
Add 7:45, 1h 30m, 45m and 2.5
- Time worked
- 12h 30m
- In decimal hours
- 12.5
4 times added together come to 12h 30m (12.5 hours).
How the calculation works
Time between two times = end − start, minus any break. From 09:00 to 17:30 is 8 hours 30 minutes; take off a 30 minute break and it's 8 hours. If the end time is earlier than the start (a night shift), the calculator counts across midnight: 22:00 to 06:00 is 8 hours.
Decimal hours = minutes ÷ 60. So 8 hours 45 minutes is 8 + 45 ÷ 60 = 8.75 hours.
The 7:45 versus 7.45 mistake
A quarter of an hour is 0.25, not 0.15. 7 hours 45 minutes is 7.75 hours, not 7.45. Typing minutes after a decimal point is one of the most common timesheet and invoicing errors, and it costs real money over a month.
| Minutes | Decimal hours |
|---|---|
| 10 | 0.17 |
| 15 | 0.25 |
| 20 | 0.33 |
| 30 | 0.5 |
| 45 | 0.75 |
Accepted formats
Clock times can be 24-hour (17:30, 0930) or 12-hour (5:30pm, 9am). Lengths of time can be 7:45, 7h 45m, 45m, or a plain decimal such as 1.5, which is read as 1.5 hours.
Frequently asked questions
How do I calculate hours worked?
Subtract the start time from the end time and take off any unpaid break. From 09:00 to 17:30 with a 30 minute break is 8 hours.
How do I convert hours and minutes to decimals?
Divide the minutes by 60 and add them to the hours. 7 hours 45 minutes is 7 + 45 ÷ 60 = 7.75.
How does it handle night shifts?
If the end time is earlier than the start time, it assumes the shift ended the next day. 22:00 to 06:00 is 8 hours.
Can I add up more than two times?
Yes. Switch to “Add up lengths of time” and enter up to six times in any mix of formats.
Why are minutes shown as decimals on invoices?
It makes the multiplication by an hourly rate straightforward: 8.75 hours at £20 is £175. Rounding to the nearest quarter-hour or minute is a matter for your contract.
Formulas tested against hand-worked answers. Last reviewed 29 September 2026. These calculators do arithmetic only; they are not financial, tax or legal advice.