How to calculate a time duration
- Convert both times to minutes after midnight. 9:15 AM is 9 × 60 + 15 = 555, and 5:05 PM is 17 × 60 + 5 = 1,025.
- Subtract: 1,025 − 555 = 470 minutes.
- Convert back: 470 ÷ 60 = 7 hours, with 50 minutes left over.
If the end time is earlier than the start time, the period runs past midnight, so add 24 hours (1,440 minutes) to the end time first.
Decimal hours
Timesheets and payroll often need hours as a decimal. Divide the minutes by 60: 7 hours 50 minutes is 7.83 hours. Some common conversions:
| Minutes | Decimal | Minutes | Decimal |
|---|
| 15 | 0.25 | 45 | 0.75 |
| 20 | 0.33 | 50 | 0.83 |
| 30 | 0.50 | 10 | 0.17 |
Common uses
- Working out how long a shift lasted after a lunch break.
- Timing a flight, drive or meeting.
- Finding when a task will finish if it starts now and takes a set time.
Tracking a whole week of shifts? The time card calculator totals every day and works out pay.
Last reviewed October 2026.
Frequently asked questions
How do I calculate the time between two times?
Subtract the start time from the end time. If the end time is earlier than the start, the period crosses midnight, so add 24 hours. From 10:00 PM to 6:30 AM is 8 hours 30 minutes.
How do I convert hours and minutes to decimal hours?
Divide the minutes by 60 and add them to the hours. 7 hours 45 minutes is 7 + 45 ÷ 60 = 7.75 hours. Payroll systems often use decimal hours.
Can I subtract a break?
Yes. Enter the break length in minutes and it is taken off the total. This is handy for working out paid hours on a shift with an unpaid lunch break.
How do I add hours to a time?
Switch to "Add time" mode, enter a start time and how many hours and minutes to add. For example, 9:15 AM plus 7 hours 50 minutes is 5:05 PM.
Does it work with a 24-hour clock?
Yes. Time fields follow your device settings, so they may show AM/PM or a 24-hour clock. Results are shown in both formats.