⏱️ Stopwatch
Online stopwatch with lap timing. Millisecond precision. Start, pause, lap, reset.
A browser-based stopwatch with millisecond precision and lap timing. Start, pause, resume, and record split times — each lap shows cumulative total and delta from the previous lap in a three-column table. The timer uses system-time-based elapsed calculation via performance.now(), staying accurate even in background tabs. Display updates via requestAnimationFrame for smooth rendering. No install required.
📋 When to Use the Stopwatch
The Stopwatch covers anything you time by hand — workout circuits, presentation rehearsals, process steps in a runbook, a kettle you keep forgetting. Lap timing makes it genuinely useful for interval training and split-based comparisons rather than just a running count.
⚙️ How the Stopwatch Works
Elapsed time is computed from the system clock via performance.now(), which keeps the count accurate even when the tab is backgrounded, while the display repaints smoothly through requestAnimationFrame. Start, pause, and resume preserve the total exactly; each lap records both the cumulative time and the delta from the previous lap in a three-column table.
How to Use the Stopwatch
- Click Start — The timer begins counting with millisecond precision.
- Record laps — Click the Lap button (appears after starting) to capture split times. Each lap is listed below.
- Pause and resume — The Start button toggles between Start and Pause. Laps and elapsed time are preserved while paused.
- Reset to zero — Click Reset to clear the timer and all lap records, returning to 00:00.000.
Frequently Asked Questions
How accurate is the stopwatch?
The stopwatch uses JavaScript's high-resolution timer for millisecond precision. It's accurate enough for sports timing, experiments, and productivity tracking — but not for professional race timing.
Does it keep running if I switch tabs?
Yes! The stopwatch continues running even when the tab is in the background. The display updates based on elapsed system time, so it stays accurate.
Can I export my lap times?
Currently, lap times are displayed in the browser only. You can copy them manually or take a screenshot.
What's the maximum time?
The stopwatch can run indefinitely — hours, days, or longer. There's no built-in time limit.
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