⏱️ Stopwatch
A stopwatch with lap recording. The fastest and slowest laps are automatically highlighted, making it useful for reviewing training splits or timing a sports session.
How to use
- Click "Start" to begin timing.
- Click "Lap" each time you want to record the elapsed time so far.
- Click "Stop" to end timing, and "Reset" to clear the recorded laps.
How the calculation works
This stopwatch measures elapsed time to 1/100 of a second. Press Lap to record the total time so far and the split, the time since the previous lap. Elapsed time is measured with the browser’s dedicated elapsed-time clock (performance.now). It is not affected by changes to the device clock, so an automatic clock adjustment during timing does not throw the result off. Once you have two or more laps, the lap with the shortest split (fastest) and the longest split (slowest) are highlighted.
Worked example
Three laps of a 400 m track Lap 1: split 01:42.15 / total 01:42.15 Lap 2: split 01:45.80 / total 03:27.95 Lap 3: split 01:39.60 / total 05:07.55 Lap 3 is highlighted as the fastest and lap 2 as the slowest.
Things to be aware of
- Human reaction time adds about 0.1–0.3 s when pressing a button. Use dedicated timing equipment for official records.
- Closing or reloading the page clears the running time and the laps.
- The display shows hundredths, and each lap records the exact moment you pressed the button.
FAQ
Is there a limit to how many laps I can record?
No, you can record as many laps as you like for as long as you keep timing.
Can I pause and resume?
Yes — resuming continues from where you stopped, keeping the elapsed time so far.
Is this useful for reviewing training splits?
Yes — record laps during a run or swim, and the fastest and slowest laps are highlighted automatically, making it easy to see how consistent your pace was.
Is it easy to use one-handed during a workout?
Yes — the buttons are designed to be large and easy to tap, so you can record a lap one-handed while exercising.
Can I copy or export the results?
The current version shows the lap list on screen only; jot down anything you want to keep a permanent record of.