Online Stopwatch

Time anything with a precise stopwatch and lap splits.

Runs locallyWorks offlineShare link carries settings, never your data
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Frequently asked questions

How accurate is a browser stopwatch?

It uses a high-resolution timestamp clock, so it is accurate to well within a hundredth of a second — far finer than human reaction time, which is around two tenths. Your reflexes, not the timer, are the limiting factor.

What are lap times for?

A lap records a split without stopping the clock, so you can compare individual intervals across a session — per-length swim times, or how long each stage of a process takes.

Does it keep timing in a background tab?

Yes. Elapsed time is derived from timestamps rather than an interval counter, so switching tabs or minimising the window does not cause the drift you get from naive implementations.

Pro tips

  • Leave the tab visible for anything where the alert matters; browsers may delay notifications from a heavily throttled background tab.
  • Use laps rather than stopping and restarting, so you keep both the interval times and the running total.
  • Note that the fastest and slowest laps are marked for you — comparing intervals is usually the reason for recording them at all.
  • Set the countdown before you need it. Fumbling the duration while something is already cooking defeats the purpose.
  • Check your device is not muted before relying on an audible alert, particularly on a phone with a physical silent switch.

About Stopwatch & Timer

Each lap shows its own time next to the running total, with the fastest and slowest marked, because comparing one interval against another is the entire point of recording them. The clock is high-resolution rather than a once-a-second tick, so a long session does not drift.

Start a precise stopwatch and capture lap splits to compare intervals, with a countdown timer in the same view. It runs entirely in your browser.

Time anything with a lap-recording stopwatch, or count down from any duration with a clear time's-up alert — both in one tool. Use the stopwatch for workouts, cooking and speed tests, and the countdown for breaks, presentations and kitchen timers.

Record laps to compare one interval against another, or switch to the countdown for a fixed duration with an alert at the end. Both share a tab, so timing a workout and its rest period does not mean swapping tools.

Browser timers are a request rather than a promise, which is why so many web stopwatches drift. Asking to be called every second returns control a few milliseconds late each time, and counting those callbacks accumulates every delay — over a long session the error grows to tens of seconds. Reading the clock and computing the difference from the start instead means a delayed frame affects only how often the display refreshes, never the elapsed value.

Background tabs make the distinction stark. Browsers throttle inactive tabs aggressively to save battery, so a tick-counting timer slows or effectively stops the moment you switch away — which is exactly what someone starting a focus timer then going to work does. A clock-reading timer is immune: whatever the tab was doing, the elapsed time is correct the instant it wakes.

Common use cases

  • Timing laps during training without a dedicated watch
  • Measuring how long a manual process actually takes
  • Timing rounds in a game or classroom activity
How it comparesA phone's built-in clock app is more reliable for an alarm that must fire while the screen is off, because the operating system guarantees it and a browser tab cannot. On a desktop where you are already working, a tab is faster to reach and easier to read from a distance.