Time Duration Calculator
Elapsed time between clock times
An end time earlier than the start automatically means the next day. Use the switch for equal or later clock times on the next day.
- Duration (hours:minutes)
- 8:30
- Total minutes
- 510
- Decimal hours
- 8.5
Clock-time arithmetic only: no dates, time zones, or daylight-saving adjustments. Use the date calculator for calendar intervals.
Add or subtract durations
- Duration (hours:minutes)
- 4:15
- Total minutes
- 255
- Decimal hours
- 4.25
Hours do not wrap at 24. Enter whole hours (0–1,000,000) and minutes (0–59). Subtraction can return a negative duration.
Processed locally in your browser. Your input is not uploaded or saved by this tool.
How it works
Choose start and end clock times for elapsed time. Earlier end times automatically cross midnight; mark next day explicitly for equal or later end times. In the second panel, enter two durations to add them or subtract the second from the first. Results include hours:minutes, total minutes, and decimal hours.
Example
22:30 to 06:15 is 7 hours 45 minutes overnight. Adding 2:30 and 1:45 gives 4:15. Subtracting 2:30 from 1:45 gives −0:45, or −0.75 decimal hours.
Frequently asked questions
How do I calculate a full 24 hours?
Use the same start and end time and enable next day. Without the switch, equal clock times mean zero elapsed time. An explicit next-day end can also produce an interval longer than 24 hours.
Does 1:30 mean 1.30 decimal hours?
No. 1:30 means 1 hour and 30 minutes, which is 1.5 decimal hours. This calculator shows both formats.