Total time
4:15:00
2:30:00 + 1:45:00
Decimal hours
4.25 hours
Learn more
How this calculator works and what to know before using it
What this calculator does
Adds or subtracts time durations, or adds a duration to a clock time.
How to use it
- Choose add durations, subtract durations, or add to a clock time.
- Enter hours, minutes, and seconds (or start time plus duration).
Formula used
Duration in seconds
Durations convert to seconds, combine, then format as H:MM:SS.
Source. Hours, minutes, and seconds are converted to seconds, added or subtracted, then shown again as hours, minutes, and seconds. A clock result uses a 12-hour clock.
Updated November 1, 2026
Example
2:30:00 + 1:45:00 = 4:15:00. Adding 2h 15m to 9:00 AM → 11:15 AM.
Good to know
- Clock times display in 12-hour AM/PM format.
Common questions
- How do I add hours and minutes together?
- Enter each duration in hours, minutes, and seconds and choose Add. The calculator handles carry-over (e.g. 90 minutes → 1h 30m).
- Can I subtract one duration from another?
- Yes — choose Subtract and enter both durations. If the second is larger, the result shows as negative.
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