Online Stopwatch
A precise online stopwatch with lap times, keyboard shortcuts and millisecond display. Accurate in background tabs. Free, no signup.
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Space starts and stops, L records a lap.
What this tool is for
Start, stop, lap. Timing is taken from a monotonic clock, so accuracy does not depend on how often the page repaints, and laps show both the split and the cumulative time. Space starts and stops, L records a lap.
How to use it
- Press start, or hit the space bar.
- Record laps with the lap button or the L key.
- Read each lap split alongside the total, and copy the results when you are done.
Frequently asked questions
How accurate is it?
It reads performance.now(), a monotonic clock with sub-millisecond resolution that is unaffected by system clock changes. Your reaction time is by far the larger error.