Online Stopwatch – Stop Clock with Laps and Full Screen
Start, pause and lap with one click or with your keyboard. The stopwatch shows hours, minutes, seconds and hundredths, and keeps running even if you reload the page.
Press Start (or the Space bar) to begin timing, Lap (L) to record a lap and Reset (R) to clear. The display reads hh:mm:ss.cc: 00:01:23.45 means 1 minute, 23 seconds and 45 hundredths. A lap time is the total at that press minus the total at the previous lap.
How to use the Online Stopwatch
- Press Start or Space. Press again to pause and resume.
- Press Lap or L at the end of each lap or split.
- Check the lap table: lap time, total time, with the fastest and slowest laps highlighted. Copy the laps to a spreadsheet with one tap.
- Press Reset or R to start over. Use Full screen to show a big stopwatch to a room.
While it runs, the browser tab shows the time, so you can follow it from another tab.
Lap time vs split time
A lap time is the time for one lap only; a split time (total) is the time since the start. The table shows both.
| Lap | Lap time | Total (split) |
|---|---|---|
| 1 | 01:32.10 | 01:32.10 |
| 2 | 01:28.75 (fastest) | 03:00.85 |
| 3 | 01:35.40 (slowest) | 04:36.25 |
For a 1,600 m run on a 400 m track, press Lap each time you pass the line to see whether you are speeding up or slowing down.
How accurate is an online stopwatch?
The stopwatch measures time with the browser’s high-resolution clock (performance.now()), not by counting screen updates, so it does not drift even if the display stutters or the tab is in the background. The display shows hundredths of a second. Your own reaction time is the real limit: pressing a button takes most people about 0.2 seconds, so hand timing is usually accurate to around a tenth of a second, which is why official races use electronic timing.
Keyboard shortcuts
- Space: start / pause / resume
- L: lap
- R: reset
Shortcuts work whenever you are not typing in a text box.
Uses
- Sport and fitness: laps, intervals, plank holds and rest periods.
- Speedruns and games: time a level or a puzzle in full-screen mode.
- Study and work: track how long tasks really take.
- Classroom and presentations: time experiments, speeches and quizzes on the big screen.
- Cooking: see how long something has been in the oven.
How long can it run?
There is no time limit. After 99 hours the hours simply keep counting. The time is stored in your browser, so closing the tab or reloading the page does not reset it.
Related tools: Online Timer, Online Clock and CPS Test.
Frequently asked questions
Does the stopwatch keep running if I close the tab?
Yes. The start time is saved in your browser, so when you open the page again the stopwatch shows the correct running time.
How do I record lap times?
Press Lap or the L key at the end of each lap. The table shows each lap time, the total and the fastest and slowest laps.
What is the difference between a lap and a split?
A lap time is the duration of one lap; a split is the total time from the start to that point.
Can I use the stopwatch full screen?
Yes. Press Full screen to show a large display, ideal for classrooms, gyms and streams.
How precise is it?
It shows hundredths of a second and uses the browser’s high-resolution clock, so it does not drift. Hand timing adds your reaction time.
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