About this tool
What does it do?
A precise stopwatch with splits/laps in your browser — for timing talks, workouts, sprints and benchmarks, with millisecond display.
How to use it
- Start, mark laps without stopping, pause and reset.
- Copy lap tables for logs.
- Fullscreen for stage visibility.
Examples
- Timing lightning talks against a 5-minute slot.
- Lap splits for interval training.
- Measuring page-load regressions by hand.
Important limitations
- Human reaction adds ~200ms error — fine for talks, not for physics.
- Background tabs may throttle timers; keep the tab visible for precision.
- For sub-millisecond needs use performance.now() in code, not a stopwatch.
Privacy
Runs locally. No timing data leaves your browser.
Frequently asked questions
How accurate?
Millisecond display, human-limited precision — good to ~0.2s in practice.
Does it run in background?
Less reliably — browsers throttle hidden tabs to save battery.
Lap vs split?
Lap resets the segment clock; split shows cumulative race time.