How accurate is the stopwatch?

The stopwatch uses performance.now() for millisecond-level accuracy — within 1-5ms for all practical purposes.

Does it stop when I switch tabs?

No — it references your system clock so it stays accurate when switching tabs or minimizing the window.

🏃 Online Stopwatch

Millisecond precision · Unlimited laps · Best/worst highlighting

00:00:00.000

How to Use the Online Stopwatch

Press the green Start button to begin counting up from zero. The display updates in real time showing hours, minutes, seconds and milliseconds. While running, press Lap to record a split time — each lap appears in the table below showing both the individual lap duration and the cumulative total elapsed time.

The fastest lap is automatically highlighted in green and the slowest in red. Press Start again to pause the stopwatch, and again to resume. Reset clears everything back to zero. Use the Copy button to export all lap data to your clipboard for pasting into a spreadsheet.

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Millisecond Precision

Uses performance.now() for sub-millisecond timing resolution — significantly more accurate than basic JavaScript timers.

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Unlimited Laps

Record as many split times as needed. The table scrolls to accommodate any number of laps without losing data.

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Auto Best/Worst

Best lap highlighted green, worst in red — automatically recalculated with every new lap added.

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Copy Lap Data

Export all lap times to clipboard in one click — paste directly into Excel, Google Sheets or any text app.

Who Uses an Online Stopwatch?

Athletes time sprints and swimming lengths. Developers benchmark code execution. Teachers manage classroom activities. Speakers practice presentations. Gamers time speedruns. The common thread: any situation requiring precise elapsed time measurement, instantly, with zero setup.

Stopwatch vs Timer vs Alarm

A stopwatch counts up — use it to measure how long something takes. A timer counts down from a set duration — use it when you want an alert after X minutes. An alarm clock fires at a specific time of day — use it for scheduled events.

Popular Uses for a Stopwatch

Athletics: Time sprints, swimming laps, cycling segments, and any race where elapsed time matters.
Fitness training: Track rest periods between sets, HIIT work phases, plank holds, and circuit completions.
Public speaking: Practice speeches with lap marks at each section to ensure correct timing throughout.
Coding and development: Measure algorithm speed, page load times, and API response benchmarks.
Classroom: Time reading comprehension tests, lab experiments, and student presentations.
Productivity: Measure exactly how long specific tasks take — invaluable for freelancers billing by the hour.
Speedrunning: Time video game speedruns with lap marks at key checkpoints for comparison across attempts.
Cooking: Time each step in a recipe precisely when developing dishes for consistent replication.

Frequently Asked Questions

How accurate is the online stopwatch?

The stopwatch uses performance.now() for sub-millisecond timing resolution — far more accurate than Date.now(). For practical purposes, accuracy is within 1–5 milliseconds, which is sufficient for athletics, cooking, presentations and all human-scale timing needs.

Does the stopwatch stop when I switch browser tabs?

No — the stopwatch references your system's high-resolution clock and continues running accurately when you switch to other tabs or minimize the browser window. The elapsed time is tracked independently of tab visibility.

Can I record lap times?

Yes — press the Lap button while the stopwatch is running to record a split time. The table shows each lap's individual duration and the cumulative total. Best lap is highlighted green, worst in red. You can record unlimited laps and copy them all to clipboard with one click.

How do I export my lap times?

Click the Copy button above the lap table. All lap data is copied to your clipboard as tab-separated text including lap number, individual lap time, and cumulative total. Paste directly into Excel or Google Sheets for further analysis.

Is the stopwatch free?

Completely free. No registration or payment is required to access millisecond precision, unlimited laps, or any other feature.

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