Stopwatch
Start, lap, and stop timing — accurate to the hundredth of a second.
A simple stopwatch with start, pause, resume, lap, and reset — runs in the tab, accurate to hundredths of a second. Free, with no app to download or install.
How to use the stopwatch
- Start begins timing.
- Pause stops the clock without losing the time; press it again to resume.
- Lap records the time on the clock at that moment, while the stopwatch keeps running.
- Reset clears the time and all laps.
Reading your lap times
Each lap shows the total time on the stopwatch when you pressed Lap. To find how long a single lap took, subtract the previous lap from it. For example, if Lap 1 shows 1:52.40 and Lap 2 shows 3:41.15, the second lap took 1:48.75.
What people time with it
- Running and swimming: time each lap of a 400 m track or a pool length to check your pacing.
- Speeches and presentations: rehearse to see whether you fit your time slot.
- Science class: time experiments such as pendulum swings or reaction times.
- Work tasks: find out how long routine jobs really take, to plan your day better.
- Puzzles and games: time a Rubik's cube solve or a board game turn.
Accuracy
The stopwatch measures real elapsed time with your browser's high-precision timer, so it doesn't drift during long sessions. The limit is human reaction time: pressing a button by hand usually adds or loses about 0.1–0.2 seconds, which matters only when comparing very close results.
Need to count down from a set time instead? Use the countdown timer. Working out your running pace from a time? Try the running pace calculator.
Frequently asked questions
How accurate is it?
It updates continuously and displays to the hundredth of a second, using your browser's high-resolution timer rather than counting in fixed steps, so it doesn't drift during longer runs.
Will it keep running if I switch to another tab?
Yes — timing is based on elapsed real time, not how often the tab redraws, so pausing and resuming (or switching tabs and coming back) still gives an accurate total.
Does it keep running if my screen locks?
The timing is based on the real clock, so when you unlock your phone and return to the page, the time shown is still correct — even if the display stopped updating while it was locked.
Is there a time limit?
No. You can leave it running for hours; the display simply keeps counting.