High-precision digital stopwatch with split lap tracking, fastest/slowest lap calculation, and elapsed time diagnostics.
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About Chronometer
A browser stopwatch with start, pause, lap and reset, shown to the millisecond. Each lap records its own time and the cumulative split, and the lap list shows the average, fastest, slowest and standard deviation, plus each lap's difference from the average. Timing uses performance.now(), which is monotonic and not affected by system clock changes, and laps can be exported as CSV.
Common uses
- Time repeated runs of a manual task or test
- Measure laps in a workout or race
- Time talks, meetings or presentation sections
- Export lap times to a spreadsheet for analysis
FAQ
- Are there keyboard shortcuts?
- Yes. Space starts and pauses, L records a lap and R resets, as long as focus is not in a text field.
- What is the difference between lap time and split time?
- Lap time is the duration of that lap alone. Split time is the total elapsed time from the start up to the end of that lap.
- How accurate is a browser stopwatch?
- Elapsed time is measured with performance.now(), which has sub-millisecond resolution, though browsers may reduce precision slightly for privacy. The display refreshes once per animation frame, but the recorded times are not limited by the refresh rate.