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Kordu Tools
Time & Date Runs in browser Updated 30 Mar 2026

Stopwatch

Precise stopwatch with lap times, split tracking, and millisecond accuracy.

00:00:00.00

The stopwatch uses requestAnimationFrame for smooth, high-resolution timing. Accuracy depends on your browser and system load.
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How to use Stopwatch

  1. Start the stopwatch

    Click 'Start' to begin timing. The display updates smoothly in real time showing hours, minutes, seconds, and centiseconds.

  2. Record laps

    Click 'Lap' at any point to record the current split. Each lap entry shows the time since the previous lap and the total elapsed time.

  3. Stop and resume

    Click 'Stop' to pause. Click 'Resume' to continue from exactly where you left off — elapsed time accumulates correctly.

  4. Review lap history

    Scroll through the lap table to review all recorded splits and cumulative times in order.

  5. Reset when done

    Click 'Reset' to clear the elapsed time and all recorded laps, returning to zero.

Stopwatch FAQ

How accurate is the stopwatch?
The stopwatch uses performance.now() for sub-millisecond timestamp resolution, updated via requestAnimationFrame at the display's refresh rate. Practical accuracy is within a few milliseconds, limited by browser scheduling and system load — not the timing algorithm.

What is the difference between split time and cumulative time?
Split time (also called lap time) is the elapsed time since the previous lap was recorded. Cumulative time is the total time from when the stopwatch started to when the lap was recorded. Both are shown for every lap.

Can I record multiple laps?
Yes. Click the Lap button as many times as needed. There is no practical limit to the number of laps you can record.

Does it keep running in the background?
The display may be throttled when the tab is in the background, but the underlying timestamp is preserved. When you return to the tab, the correct elapsed time is shown immediately.

Does the stopwatch reset on page refresh?
Yes. Elapsed time and lap records are held in memory only. Refreshing the page resets the stopwatch to zero. If you need to preserve timings, note them before refreshing.

Can I use keyboard shortcuts?
Keyboard shortcuts are supported. Space bar starts and stops the timer; the L key records a lap. This lets you time events without moving your hands from the keyboard.

What is the maximum time it can measure?
The display supports hours, so it can run continuously for any practical duration. There is no hard limit — it will keep timing as long as the tab stays open.

Is this suitable for sports timing?
Yes for personal training and informal timing. For official competitive events requiring certified accuracy (swimming, athletics), use a purpose-built sports timer with hardware-level precision.

Is any data sent to a server?
No. The stopwatch runs entirely in your browser. Lap times are held in memory only and are cleared on reset or page refresh.

Background

A browser-based stopwatch with start, stop, resume, and reset controls. Record lap times to track splits and see the elapsed time between each lap alongside the cumulative total. The display shows hours, minutes, seconds, and centiseconds, updated smoothly every frame using requestAnimationFrame and performance.now() for high-resolution timing accurate to sub-millisecond resolution. Lap records show both the split time (time since the previous lap) and cumulative elapsed time. Useful for sports timing, cooking, lab experiments, productivity tracking, or any task requiring precise elapsed time measurement. Keyboard shortcuts let you start, stop, and record laps without moving your hands. Everything runs in your browser with no data transmitted or stored.

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