EN
PT
ES
Stopwatch
A precise online stopwatch with millisecond resolution, lap times and keyboard shortcuts.
What this stopwatch does
A traditional stopwatch with millisecond precision. Start, pause, resume, take lap times, and reset to zero. Each lap shows both the split (time since the last lap) and the cumulative total. The fastest lap is highlighted in green, the slowest in red, so it's easy to spot the best and worst moments of a session.
How to use the stopwatch
- Press Start (or hit Space) to begin counting up from zero. The display updates many times a second.
- Press Lap (or L) at any moment to record a split. Laps stack with the most recent on top, and the best/worst splits are colour-coded automatically.
- Press Pause to stop the clock without losing the elapsed value, and press it again ("Resume") to keep going.
- Press Reset (or R) to clear the elapsed time and the lap list.
About the precision
The stopwatch uses your browser's high-resolution timer (performance.now()), which is independent of the system wall clock and unaffected by clock changes or NTP corrections. Each frame redraws the display, so what you see is accurate to within a single animation frame (typically 16ms) — and laps are stamped at the exact instant you click, regardless of when the next frame paints.
Keyboard shortcuts
Space — start, pause, or resume. L — record a lap. R — reset to zero. Shortcuts are ignored while typing in a field, so you can have other inputs on the page without conflicts.
Frequently asked questions
How accurate is the stopwatch?
performance.now(), a monotonic high-resolution clock that doesn't jump if your system clock is corrected by NTP. The display refreshes once per animation frame (typically 16ms), but the underlying value tracks elapsed time precisely and lap stamps are taken at the moment of the click.