Stopwatch & Timer
Time something with a lap-recording stopwatch, or count down with a timer that sounds when it reaches zero. Both read their elapsed time from the system clock rather than by adding up ticks, which is the detail that matters: a browser slows down or suspends timers in a background tab, and a counter built on ticks quietly falls behind while one built on the clock stays right. So you can start a timer, switch tabs, and come back to the correct figure. No installs, no sign-up, and nothing to remember to close.
How to use
- Pick a mode: Stopwatch or Timer.
- Stopwatch: press Start, record laps, and reset when done.
- Timer: set hours, minutes, and seconds, then start.
- The timer plays an alarm sound when it finishes.
- Pause and resume the timer any time.
Frequently asked questions
- Does it stay accurate in the background?
- Yes. Timing is based on the system clock (Date.now), so the elapsed and remaining times stay correct even if the tab is inactive.
- Will the alarm sound play?
- It uses the Web Audio API and plays after you've started the timer. Make sure your device isn't muted.
- Are my times saved?
- No. This tool keeps nothing — reloading the page clears the stopwatch and timer.
- How precise is the stopwatch?
- It displays hundredths of a second and is driven by the high-resolution system clock.
- Why does the display jump when I return to the tab?
- Because the redraw was throttled while the tab was hidden, not because time was lost. Elapsed time is recomputed from the system clock every update, so the moment the tab is visible again the display catches up to the true figure in one step. The number was always right; it just was not being painted.
- Will the timer still fire if I lock my phone?
- It may not fire on time. Mobile browsers suspend background pages aggressively to save battery, and a suspended page cannot play a sound at the appointed moment - it will notice it has run out only when you return to it. For anything you must not miss, use your device's own alarm; a browser tab is not the right place for it.
- What is the difference between a lap and a split?
- A lap is the time for one segment, measured from the previous lap. A split is the total elapsed at that point, measured from the start. This stopwatch records the running total each time you press lap, so the split is what you see directly and the individual lap time is the difference between two consecutive entries.
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