Stopwatch Online
Free online stopwatch with lap timer — record split times, track fastest and slowest laps, export to CSV. No ads, no signup required.
Updated May 2026
PRECISION STOPWATCH
Space = Start/Pause · L = Lap · R = Reset
Lap History
No laps recorded yet.
Real-time Analytics
TOTAL LAPS
0
AVERAGE LAP
--:--.--
FASTEST
--:--
SLOWEST
--:--
How to use the online stopwatch
Record laps without ever stopping the clock
1. Press Space or Start
The stopwatch starts counting from 00:00:00.000, updating 60 times per second.
2. Press L or Lap
The current split is logged to the table without interrupting the count — lap time and running total both saved.
3. Export or reset
Download a CSV that opens in Excel, Sheets, or Python, or press R to start a fresh session.
What this online stopwatch can do
High-resolution performance.now() timing, even in a background tab
Keeps running when you switch tabs
Built on performance.now(), the browser's monotonic clock, which is immune to the throttling that slows down setInterval in background tabs.
Live stats while you run
Fastest lap, slowest lap, and average lap time are calculated automatically after every split you record.
One-click CSV export
Download lap number, individual lap time, and running total — ready to drop into Excel, Sheets, Python, or R.
Built for long sessions
HH:MM:SS.mmm format supports sessions up to 99:59:59.999 without losing precision.
Example use cases
How people actually use the lap timer
When you'll reach for this stopwatch
The most common scenarios among people who use this tool
Running and track workouts
Log every 400m or 1km split and see at a glance whether your pace is holding steady, fading, or improving.
Classroom timing
Record how long each student takes to finish a task without pausing the master clock.
Lab and research timing
Capture reaction times or intervals between events, then export the data to Excel, Python, or R for analysis.
Cooking and recipe development
Compare how long each stage of a recipe actually takes across different attempts.
Common mistake? Start here
Forgetting to press Lap mid-session
The total time stays accurate, but a missed lap can't be reconstructed afterward — there's no way to insert a split retroactively.
Expecting electronic-sensor precision
Your own reaction time (roughly ±150-250ms per click) is the limiting factor, not the browser clock's resolution.
Mixing up stopwatch and timer
A stopwatch counts up (how long something took); a timer counts down (alerts you when a set period ends).
Why use this stopwatch
It's built on performance.now(), a sub-millisecond clock that's technically more precise than most handheld digital stopwatches — and it keeps counting accurately even when the tab is in the background, unlike timers built on setInterval.
CSV export with lap number, individual time, and running total removes the manual transcription step for anyone who needs to analyze the data afterward, whether that's a coach, a teacher, or a researcher.
Stopwatch vs. timer
Opposite directions of counting
Frequently asked questions
Yes. It's built on performance.now(), the browser's monotonic clock, which keeps advancing regardless of tab visibility or the background throttling that affects setInterval-based timers.
References
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