Online Stopwatch

A precise, distraction-free stopwatch with lap history, keyboard shortcuts and CSV export.

00:00:00.00

hours · minutes · seconds · centiseconds

Keyboard: Space start/pause · L lap · R reset · F fullscreen

How to use this stopwatch

Press Start or hit the Space bar to begin timing. Tap Lap (or press L) to record splits. Press R to reset and F for fullscreen mode. Your best lap is highlighted in green.

Features

Millisecond precision (centisecond display)
Unlimited lap history with split & total times
Export all laps to a CSV file for later analysis
Full keyboard shortcuts and fullscreen mode
Dark mode, mobile responsive, works offline

A stopwatch is one of the oldest, most useful tools in the human toolbox — used everywhere from track meets and cooking to lab experiments and speech-timing. Our online stopwatch was built to be the fastest, cleanest, most accurate one you can use in a browser. It runs entirely in your device, uses your CPU's high-resolution timer, and never sends a single millisecond of data anywhere else.

How it works

Under the hood the stopwatch uses the browser's `performance.now()` API which is accurate to sub-millisecond precision on modern devices. Each animation frame (roughly 60 times per second) we recompute the elapsed time by subtracting the start timestamp from the current one. This is far more accurate than `setInterval()` because it isn't affected by JavaScript event-loop delays. The result: a stopwatch that keeps accurate time even under heavy CPU load.

Key features

Millisecond precision (centiseconds displayed)
Unlimited lap history with automatic split calculation
Best-lap highlight in green so trends are obvious
Full keyboard shortcuts: Space start/pause, L lap, R reset, F fullscreen
CSV export for spreadsheet analysis
Dark mode and mobile responsive
Works offline as a PWA
Zero tracking — everything stays in your browser

Common use cases

Athletics & training

Time sprints, rest periods and repetitions. Multiple laps let you compare each rep and spot fatigue patterns across a workout.

Cooking & baking

Precisely time delicate operations like tempering chocolate, boiling eggs or proofing dough where seconds matter.

Meetings & presentations

Keep a fair speaking clock during panels, debate practice or job interviews. Fullscreen mode makes the time visible from across a room.

Science & lab work

Record split times for reactions or observations. CSV export makes it trivial to import data into Google Sheets, Excel or R for analysis.

Pro tips

◆Press F for fullscreen when you need to see the timer from far away.
◆Your best split is highlighted automatically — no math needed.
◆Copy the current time to clipboard with the copy icon for quick sharing.
◆Export laps as CSV to chart trends across multiple sessions.
◆On mobile, add to home screen for a native-app feel.

Common mistakes to avoid

✕Forgetting to reset between sessions — always press R before a new run.
✕Confusing split time (time since last lap) with total time (time since Start).
✕Relying on a stopwatch for legally-precise timing — always use certified equipment for anything that carries financial or legal weight.

Frequently asked questions

How accurate is this stopwatch?▼

Sub-10-millisecond accuracy on any modern device. That's dramatically more accurate than any physical hand-operated stopwatch (human reaction time is around 250 ms).

Does the stopwatch keep running if I switch tabs?▼

Yes. The elapsed time is calculated from the difference between start and current timestamps, not by counting ticks, so it stays perfectly accurate even in background tabs.

Can I save my laps?▼

Click the download icon to export them as a CSV file you can open in Excel, Numbers or Google Sheets.

Does it work offline?▼

Yes, TimeStopwatch is a Progressive Web App. Once the page has loaded once, the stopwatch works with zero internet connection.

Is my data private?▼

Absolutely. Nothing is ever sent to our servers. Your laps, settings and times exist only inside your browser.