How it works
The stopwatch counts up from zero and records lap times. Like the countdown timer it reads the system clock, so the elapsed time is right to the millisecond even if the browser throttles the tab.
- Press start — or the space bar.
- Press lap to record a split without stopping the clock.
- Stop and reset when you are done; laps stay on screen until you reset.
For counting down to zero instead, use the countdown timer.
Examples
What laps are for:
- Running: one lap per kilometre shows whether you are slowing down.
- Workouts: a lap per set, to compare rest times.
- Presentations: a lap per section, to see which one always overruns.
Stopwatch: frequently asked questions
- How precise is this stopwatch?
- It displays hundredths of a second, measured from your device clock.
- What is a lap time?
- The time for one segment (e.g. one lap of a track), recorded without stopping the overall timer.
- How accurate is the online stopwatch?
It reads the system clock in milliseconds, so it is accurate to well under a tenth of a second — far finer than human reaction time.
- What are lap times for?
A lap records a split without stopping the clock, so you can compare each kilometre, set or section afterwards.
- Does it keep counting if I switch tabs?
Yes. The elapsed time is worked out from the start timestamp, so background throttling does not affect it.