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00:00.000

Stopwatch

100% Free

Millisecond precision stopwatch with lap splits, fastest/slowest highlighting, and one-click copy of results.

Milliseconds
Lap Splits
Real-time
No Login
00:00.000

Space start/pause · L lap · R reset

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  • Responsive design
  • Lightweight & fast
  • No backend required
  • Always up-to-date 
<iframe
  src="https://tools.town/embed/stopwatch/"
  width="100%"
  height="600"
  style="border:none; border-radius:12px;"
  loading="lazy"
  title="Stopwatch">
</iframe>

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How to Use

  1. 1 Press Start to begin timing — the display updates every 10 ms
  2. 2 Press Lap to record a split without stopping the timer
  3. 3 Press Stop/Pause to freeze; press Start again to resume from where you left off
  4. 4 Green = fastest lap, Red = slowest — identified automatically
  5. 5 Press Copy to copy all laps as tab-separated text for a spreadsheet
  6. 6 Press Reset to clear the timer and all laps and return to 00:00.000

Features

  • Millisecond precision (10 ms update interval) — accurate even when the tab is backgrounded
  • Unlimited lap recording with per-lap duration and cumulative time columns
  • Automatic fastest (green) and slowest (red) lap highlighting across all recorded laps
  • Average lap time and total summary statistics computed in real-time
  • One-click copy of the full lap table as tab-separated text
  • Keyboard shortcuts: Space = Start/Stop, L = Lap, R = Reset for hands-free operation

Why it Matters

A stopwatch is one of the simplest measurement tools, yet precision timing matters everywhere — from running track intervals to competitive cooking, debugging server response times, or quality-checking a manufacturing step. A browser-based stopwatch runs anywhere without installing an app, and lap splits with automatic fastest/slowest detection give you the statistical summary that a phone clock never does.

★★★★★

Use Cases

Running & Fitness

Time interval training laps and compare splits to track pacing consistency

Debugging & Testing

Hand-time a UI animation, API round-trip, or test suite step with millisecond granularity

Presentations & Demos

Keep yourself on schedule during talks by timing each section against target splits

Science & Education

Record reaction times, pendulum periods, or experiment intervals with one tap

How the timer works

The stopwatch records the wall-clock instant at Start using performance.now() and subtracts it from the current time on every animation frame. This approach keeps the displayed time accurate even when the browser throttles background tabs or when system load causes a missed frame.

Lap splits explained

Each Lap press records the current elapsed time as a cumulative snapshot. The per-lap duration shown in the table is the difference between successive snapshots — identical to how a physical lap timer works. After two or more laps are recorded, the fastest lap is highlighted in green and the slowest in red so you can instantly see variance.

Privacy

All timing runs entirely in your browser. No data is sent to any server.

Frequently Asked Questions

How accurate is a browser-based stopwatch?
Modern browsers run JavaScript timers that typically have ±5–10 ms jitter depending on system load. The timer records the start timestamp using performance.now() and subtracts from the current time on each animation frame, so it stays accurate even when the browser throttles background tabs. For most purposes this is more than adequate.
Does the stopwatch keep running if I switch tabs?
Yes. The timer calculates elapsed time from a stored start timestamp rather than incrementing a counter, so it accumulates correctly even when the tab is backgrounded. The visual display pauses its updates but catches up the moment you switch back.
How many laps can I record?
There is no hard limit. The lap table renders efficiently for hundreds of entries. For very long sessions you can scroll the table or copy all laps to a spreadsheet.
What do the keyboard shortcuts do?
Space bar starts and stops the timer; L records a lap without stopping; R resets everything. These let you operate the stopwatch hands-free while timing a physical activity.
Can I export lap times?
Press Copy to copy all laps as tab-separated text (lap number, lap time, cumulative time). Paste directly into Google Sheets or Excel. CSV download is a roadmap feature.
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