Online stopwatch
A precise stopwatch with lap times. Space to start and stop, fullscreen for a classroom or a track. Runs in your browser.
00:00.00
Space to start and stop · L for a lap · F for fullscreen
Laps
No laps yet. Press L while the stopwatch runs to record a split.
How to use the stopwatch
Start it with the space bar, record laps as they happen, and read the time from across the room in fullscreen. Timing comes from the clock rather than a counter, so it stays accurate even if the browser throttles the tab.
Start and stop
Press Space or click Start. Space stops it again. The display shows minutes, seconds, and hundredths.
Take laps
Press L or click Lap while it runs. Each lap records its own split and the total elapsed at that moment, newest at the top.
Show the room
Press F for fullscreen — a dark stage with no ads and no site chrome, readable from the back of a hall.
About this tool
A stopwatch is the tool for “how long did that take”; a countdown is the tool for “how long is left”. Classrooms tend to need the second one, labs and workshops the first, which is why both live here with the same fullscreen stage.
Lap timing answers a different question again: not the total, but whether each round is getting slower. Reading the splits down the list tells you that immediately.
Frequently asked questions
- How accurate is it?
- Elapsed time is the difference between two timestamps, so it does not drift, and a background tab that stops repainting still reports the right time when you come back. Your reaction on the button is a far bigger error than the clock.
- Do laps survive a refresh?
- No. Laps live in the page. Copy them before you close the tab if you need to keep them.
- Can I use it for sport?
- For training splits, yes. For an official result, no — a hand-operated stopwatch of any kind is worth about a quarter-second either way.