How to use it
- Press Start or the space bar.
- Press Lap (or L) to save a split; each lap shows its own time and the running total.
- Press Stop to pause and Reset to clear.
Questions and answers
How accurate is it?
It reads the browser’s high-resolution clock, so it does not drift, even in a background tab. The display shows hundredths; your own reaction time when pressing the button is the main source of error.
Does it keep running if I switch tabs?
Yes. The time is calculated from the moment you started, so when you come back the display shows the exact elapsed time.
Can I use it on my phone?
Yes. Tap Start and Lap; full screen keeps the screen on in most browsers.