Stopwatch
An online stopwatch measures elapsed time to the centisecond, with start, stop, reset, and lap controls — a browser-based alternative to a physical stopwatch or phone timer app. Sampling from real timestamps rather than incrementing a counter on a fixed interval is what keeps the elapsed time accurate under real-world conditions — a throttled background tab, a brief system hiccup, or a device waking from sleep — since the displayed time is always recalculated from now minus the actual start moment.
How it works
- Click Start to begin timing.
- Click Lap to record a split without stopping the clock, or Stop to pause.
- Click Reset to clear the time and all laps.
Formula Elapsed = accumulated time + (now − start timestamp), sampled every 50ms
Frequently asked questions
How accurate is this stopwatch?
It reads your device's clock every 50 milliseconds, accurate to about a hundredth of a second for typical use — precise enough for most timing needs, though not suitable for competitive/certified timing.
Does it keep running if I switch tabs?
Yes — timing is based on real timestamps (start time vs. now), not a simple tick counter, so it stays accurate even if the browser throttles background tabs.
Can I record multiple laps?
Yes — click Lap as many times as you like while running; each lap records the total elapsed time at that moment.
Is my timing data saved anywhere?
No. Nothing is saved — reloading the page resets the stopwatch.
Does it keep counting correctly if my laptop sleeps?
Yes — because elapsed time is computed from real start/now timestamps rather than counted in ticks, the display jumps to the correct elapsed time once your device wakes, instead of losing or freezing the time spent asleep.