Online Stopwatch

How to use

Press Start to begin and Stop to freeze the time. Press it again to continue, or Reset to go back to zero. Tap Lap at each lap of a run or each slide of a talk, and every split is listed below. On a keyboard, Space (start/stop) and L (lap) are much faster than clicking.

Split vs. total

In the table, Split is the time since the previous lap and Total is the time since you started. Four laps of a 400 m track tell you both "how long was each lap" and "how long did the full 1,600 m take". From three laps on, the fastest split turns green and the slowest red, so you can see exactly where your pace dropped.

How precise is it?

The stopwatch measures with your device's high-resolution timer (performance.now), which is not affected by clock changes or time synchronisation and keeps running correctly while you look at other tabs. The display shows hundredths of a second.

The biggest error in a real measurement is your finger. Human reaction time to a visual signal is around 0.2 seconds, so a hand-timed start and stop can each be off by that much. That's why athletics treats hand-timed and electronic results differently. If you are racing friends, have the same person time everyone the same way.

To count down a fixed time, use the timer; to split study time into blocks, try the Pomodoro timer.

FAQ