Online stopwatch with laps and splits

A free online stopwatch with millisecond precision, unlimited lap and split times, a tempo sparkline, CSV export and a shareable link. Designed for sports, science labs, classrooms, cooking and time-boxed work — keeps counting accurately even when the tab is in the background.

How to use the stopwatch

Press Start

Hit the big Start button or press Space. The display counts up immediately and the screen stays awake on supported devices.

Add laps and splits

Press Lap (or L) for each interval — the table records lap time, cumulative split, and the difference from the average.

Pause, resume or reset

Space pauses and resumes without losing laps. Reset (R) asks for confirmation so you do not wipe a session by accident.

Export or share

Download a CSV, copy the table to a spreadsheet, or share a link that re-opens the same laps in a read-only view.

Time anything to the millisecond — share, export, replay

00:00:00.000

Shared session You are viewing someone else's laps in read-only mode.

Best

—

Worst

—

Average

—

Laps

No laps yet — press Lap during the run

Lap

#	Lap	Split	Δ avg
No laps yet — press Lap during the run

Space — Start / Pause
L — Add lap
R — Reset
F — Toggle fullscreen
S — Toggle sound
V — Toggle voice cue
A — Toggle analog dial
Esc — Close fullscreen / dialog

Features

Millisecond precision via performance.now() Unlimited laps with sparkline + best/worst/average CSV export and shareable result URL Wake lock keeps the phone screen on while running Voice announcements + sound cue + haptic on lap Crash-restore — laps survive accidental tab close

What you can do with this stopwatch

Time sports laps and intervals to the millisecond
Compare splits with the running average to spot fade-out
Run classroom timing with a fullscreen display visible from the back row
Save lap data to a spreadsheet via one-click CSV export
Share a frozen result with a coach or teammate by URL
Use voice cues and haptic feedback for hands-free workouts

Output formats

Lap data exports as CSV with a UTF-8 BOM for Excel compatibility, or copies as tab-separated text for direct paste into Google Sheets and Numbers. Share-laps links are stateless and self-contained — anyone opens the URL and sees the same laps.

Why this stopwatch is different

Most online stopwatches drift in background tabs because they tick a counter on setInterval — modern browsers throttle that to 1 Hz when the tab is hidden. This one stores the moment you pressed Start and recomputes elapsed time on every animation frame from performance.now(), so it never lies even after a phone call or screen-off interlude. Wake Lock keeps the display alive on mobile, a Web Worker keeps the tab title ticking when hidden, and crash-restore quietly snapshots your laps so a closed tab does not wipe a workout.

Frequently asked questions

Does the stopwatch keep counting if I switch tabs?

Yes. Elapsed time is recomputed from the moment you pressed Start each animation frame, so background-tab throttling cannot drift the result. The visible digits catch up the instant you return.

How accurate is it?

Timing uses performance.now(), a monotonic clock immune to NTP adjustments. Drift is below 5 ms per minute on modern devices. The display refresh is 100 Hz; export shows the underlying millisecond value.

Can I share my laps with someone?

Press Share — the laps are encoded in the URL and the link is copied to your clipboard. Anyone who opens it sees a read-only view of your run; they can press Start my own to clear it and use the stopwatch normally.

What happens if my browser closes by accident?

A snapshot is saved every five seconds and on every lap. When you reopen the page within 24 hours, the stopwatch offers to restore the previous session.

Will my phone screen stay on?

Yes, when the browser supports the Wake Lock API and you started the stopwatch with a tap or click. The lock releases automatically on pause and re-acquires on resume.

Can I export the laps to Excel or Google Sheets?

CSV downloads a properly BOM-tagged file that opens cleanly in Excel. Copy puts tab-separated rows on the clipboard for direct paste into Google Sheets, Numbers or any text editor.

💡 Want us to improve this tool just for you?

We can — and it's free! Just send us a quick message with your idea. If you'd like to discuss it in detail, leave your email and we'll get back to you. You can stay anonymous.

How do you rate this tool?

Thank you for your rating!

Change my rating

Want to leave a comment?

Want to share more? Leave a comment!

Thank you! Your comment will appear after moderation.

Who is this tool for?

🎮 Gamers 🎓 Students 📚 Educators & Teachers 🧘 Wellness & Meditation 🏃 Sports & Athletics 📋 Productivity

Published 08 May 2026