Stopwatch Online — Free Timer with Lap Times

Online Stopwatch

Stopwatch times anything to the hundredth of a second — sprints, workouts, cooking, presentations, speedcubing — with lap splits so you can compare segments.

It uses high-frequency updates for a smooth, accurate display, and lap times stack up in a clean list you can review at the end.

How to use the online stopwatch

1. Press Start to begin timing.
2. Tap Lap any time to record a split without stopping.
3. Press Stop to pause; Resume continues from the same time.
4. Reset clears the clock and all laps.

Key features

• 1/100s precision: hundredth-of-a-second display.
• Unlimited laps: every split recorded in order.
• Pause/resume: stop and continue without losing time.
• No install: works instantly in any browser, on any device.

Stopwatch with Laps and Milliseconds

Need a stopwatch with laps and milliseconds? This one records unlimited lap splits while the main timer keeps running, and shows time down to the hundredth of a second for precise measurement. It’s perfect for timing workouts, races, cooking, and study sessions. Everything runs right in your browser — free, with no signup or download.

Frequently asked questions

How accurate is the stopwatch?

It measures with millisecond precision using the system clock; the display updates ~30 times per second. Good enough for training and personal records.

What’s the difference between Lap and Stop?

Lap records the current time as a split and keeps the clock running; Stop pauses the clock entirely.

Can I time multiple things at once?

Open the page in two tabs — each tab runs its own independent stopwatch.

Does it work with the screen off?

On phones, the display may pause when the screen locks. Keep the screen on for critical timing.

Does this stopwatch record lap times?

Yes — press the Lap button while the timer runs to record each lap with millisecond precision, all free in your browser.

Pro Tips for Accurate Timing

• Use laps for intervals: press Lap at each round to see split times without stopping the clock — perfect for sports training and workouts.
• Keep the tab visible: browsers may throttle background tabs; for critical timing, keep the stopwatch tab in the foreground.
• Combine with the countdown timer on ShaheerTools for interval training (e.g. 30 seconds work / 10 seconds rest).

More FAQs

Can I use the stopwatch for exams or tests?

Yes — it works well for practice tests. For official exams, check the exam rules about electronic devices first.

Does the stopwatch keep running if I switch tabs?

It keeps counting, but display updates may pause in background tabs on some browsers. The final time remains accurate.

How It Works: Under the Hood

Precision comes from performance.now(), a monotonic high-resolution timer that measures milliseconds (with microsecond precision on most browsers) since the page loaded — unlike Date.now(), it isn’t affected by system clock changes or NTP adjustments mid-timing. The display updates via requestAnimationFrame, syncing redraws to your screen’s refresh rate (~60 fps), so the milliseconds you see are genuinely current, not a stuttering approximation.

Laps vs splits: a lap records the interval since the previous lap press (useful for per-round analysis), while the total keeps running uninterrupted. Both are stamped from the same monotonic clock, so lap times always sum exactly to the total — no drift, no rounding gaps.

Real-World Use Cases

• Interval training: runners time 400m repeats with lap splits, comparing each rep against target pace without stopping the clock between intervals.
• Speedcubing: cubers use the stopwatch for solves, where 0.01-second precision and spacebar start/stop (matching competition stackmats) matter.
• Lab experiments: students time chemical reactions or pendulum swings where consistent millisecond measurement beats phone-stopwatch thumb lag.
• Productivity tracking: freelancers time task segments to build accurate estimates — “this client logo actually takes 3.5 hours, not the 2 I quote.”
• Cooking multi-dish timing: home chefs run laps for each dish on the stove — pasta lap, sauce lap, garlic-bread lap — from one clock.

Advanced Tips

• Use keyboard shortcuts if available. Mouse-click latency adds 50–150 ms of human reaction time. Spacebar start/stop cuts that roughly in half for competitive timing.
• Export or screenshot lap tables. A list of 20 lap times is data — paste it into a spreadsheet to compute averages, spot your slowest rep, and track improvement week over week.
• Keep the tab in the foreground. Browsers throttle requestAnimationFrame in background tabs to save battery. The underlying clock keeps perfect time, but the display freezes — so for visual timing, keep it visible.
• Calibrate against a known standard. Time a 60-second YouTube video or metronome once. If your stopwatch reads 60.00, you can trust it for everything else.

Common Mistakes to Avoid

• Confusing lap and reset. Hitting reset instead of lap mid-session wipes everything. Learn which button is which before the important timing starts.
• Timing with the system clock. Phone clock apps that derive from wall-clock time can jump if NTP syncs mid-measurement. A monotonic-clock stopwatch like this one doesn’t have that failure mode.
• Ignoring human reaction error. Your thumb adds ~200 ms to every manual start/stop. For comparisons (before/after, A/B), the error cancels out — for absolute records, it doesn’t.
• Closing the tab mid-timing. The clock lives in the page. Closing or reloading the tab resets it — for multi-hour timing, use a dedicated device or the countdown timer as backup.

Timing Well With a Browser Stopwatch

For best accuracy, keep the stopwatch tab visible — timers in background tabs can be throttled by browsers, so switch tabs and your splits may lag. Use laps as a built-in checklist: one lap per task, per exercise set, or per study block. For the reverse job — counting down to a moment — the countdown timer has you covered, and focused work sessions pair well with the Pomodoro timer. When you need world times alongside your splits, the timezone converter is a click away.