Time Calculator
Add and subtract time durations, or find the elapsed time between two clock times. Handles overnight spans.
Runs entirely in your browser. Nothing is sent to our servers.
About this tool
Adds and subtracts time durations, or finds the gap between two clock times. Useful for timesheets, project tracking, music/audio editing, cooking, or any situation where you're juggling hours and minutes.
Duration formats accepted
- Colons:
1:30:00(1h 30m 0s),0:45:30(45m 30s),:30(30s) - Units:
1h 30m 15s,90m,5400s,2h - Decimals:
1.5h(1h 30m),0.25h(15m) - Negative (subtract): prefix with
-, e.g.-0:15:00
Use cases
- Timesheets: sum up "9:15 + 8:30 + 7:45 + 8:00 + 6:30" for the week.
- Cooking: "if I start at 4:30 PM and the dish takes 2h 15m, when does it come out?"
- Travel: "what's 3h 25m + 1h 50m of flight time + 2h layover?"
- Music: add track durations on an album mix.
Frequently asked questions
- Why doesn't the result wrap around to a clock time like 5:30 PM?
- This tool works in durations (elapsed time), not times of day. To add a duration to a clock time, use the "Time between" mode's logic: if 4:30 PM + 2h 15m, that's a clock arithmetic problem, not a duration sum.
- Can I do negative time?
- Durations can be negative — that's what subtraction does. Times of day can't. If your total comes out negative, it means subtractions exceeded additions.
- What's the largest time I can input?
- About 100 years' worth (limited by JavaScript's safe integer range applied to seconds). For sensible use, anything up to thousands of hours works fine.
Last updated: May 17, 2026