Polytimer's free online stopwatch measures elapsed time with millisecond precision — no app download, no sign-up, no ads. Start timing with a single click, record unlimited laps, and export all data to CSV. Available instantly on any desktop, phone, or tablet.
Press play or Space to start. Press L or the lap button to record a split without stopping. Press Space to pause and R to reset. All lap times are logged in a table below the display.
Yes. Press L or the lap button at any point to record a split. Each lap shows cumulative elapsed time, the individual split time, and a comparison to the average lap — with best and slowest laps highlighted in green and red.
Yes. After recording at least one lap, the Export CSV button appears. Click it to download all lap data as a CSV file compatible with Excel, Google Sheets, or any spreadsheet application.
Yes. The stopwatch measures elapsed time with millisecond precision using the browser's high-resolution performance timer. A background Web Worker keeps timing accurate even when you switch tabs or minimise the window.
Yes. Polytimer works on all modern smartphones and tablets — no app download required. Open polytimer.com/stopwatch in your mobile browser and tap play.
Polytimer displays time as HH:MM:SS.cc — hours, minutes, seconds, and hundredths of a second, read left to right. For example, 00:04:32.18 means 4 minutes, 32 seconds, and 18 hundredths elapsed. Once over an hour, the hours counter activates on the left.
A stopwatch measures elapsed time from a start point. Common uses: timing athletic performance (running, swimming, cycling laps), tracking study and work sessions, measuring experiment durations, cooking stage timing, timing presentations, and recording sports splits for analysis.
Polytimer uses the browser's high-resolution performance timer (performance.now()), accurate to microseconds. A background Web Worker tracks elapsed time even when the tab is not in focus — meaning the stopwatch stays accurate whether you switch tabs, minimise the browser, or lock your phone screen.
The stopwatch has no alarm — it counts up silently until you stop it. If you hear an alarm, it is coming from a countdown timer or Pomodoro session running in another tab. Switch to the Stopwatch tab and confirm the mode, or open the Sounds drawer to check for an active countdown.
Need a countdown instead? Try the free online countdown timer or the Pomodoro timer.