Chronometer
A stopwatch with lap times, accurate to the millisecond.
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About the chronometer
A stopwatch with lap timing, accurate to the centisecond and driven by the browser's monotonic performance clock rather than wall time. Space starts and pauses, L records a lap, R resets, and lap splits can be copied in one click.
Frequently asked questions
Is it accurate enough for benchmarking?
For anything measured by hand, yes, human reaction time swamps the timer's error. For code, use performance.now() in the code itself, since a hand-driven start adds a tenth of a second of noise.
Does it keep time if I switch tabs?
Yes. Elapsed time is calculated from timestamps rather than counted frames, so the reading stays correct even though background tabs stop repainting.