How to use
- Enter the starting time as h:mm, hh:mm, 0930 or a whole hour.
- Choose whether to add or subtract, then enter the hours and minutes.
- Read the resulting clock time and the relative day offset.
Options explained
- Start time
- A time from 00:00 through 23:59. Both 12-hour-looking entries such as 9:30 and 24-hour entries such as 21:30 are accepted.
- Duration
- Minutes range from 0 to 59, while hours can exceed 24 for calculations spanning several days.
- Day offset
- Crossing midnight shows one or more days later or earlier, so the result is not confused with the same day's time.
Examples
| Start | Operation | Duration | Result |
|---|---|---|---|
| 22:00 | Add | 8 h | 06:00, 1 day later |
| 00:15 | Subtract | 1 h 30 min | 22:45, 1 day earlier |
| 12:00 | Add | 49 h | 13:00, 2 days later |
Frequently asked questions
What time is 8 hours after 10 pm?
6:00 am on the following day. Enter 22:00, choose Add and enter 8 hours.
Can I subtract more than 24 hours?
Yes. For example, subtracting 49 hours from noon gives 11:00 two days earlier.
Does this calculator handle time zones or daylight saving time?
No. It performs clock arithmetic only. Use the time zone converter when locations or daylight saving changes matter.
Privacy
This tool runs entirely in your browser. Your files and text are processed on your device and are never uploaded to our servers.