How to use the stopwatch
- Press Start (or the spacebar) to begin timing.
- Press Lap (or L) to record a lap without stopping. Each lap shows its own time and the running total.
- Press Stop to pause and Resume to continue, or Reset (R) to start over.
- Download your laps as a CSV file to open in Excel or Google Sheets.
Lap time vs split time
A lap time is how long a single lap took — from the previous lap button press to this one. A split (shown in the Total column) is the cumulative time since you started. Runners and swimmers use lap times to check pacing and splits to track overall progress. With three or more laps, the fastest lap is highlighted green and the slowest red.
How accurate is it?
The stopwatch uses your browser’s high-resolution performance clock and displays hundredths of a second. The true limit is human reaction time — typically 0.15–0.25 seconds when pressing a button — so for official sports timing, electronic timing systems are used. For training, cooking, experiments and games, this stopwatch is more than precise enough. It keeps counting correctly even if you switch tabs.
Uses
- Running, swimming and cycling intervals.
- Timing speeches, presentations and reading practice.
- Science class experiments and reaction-time games.
- Time studies for tasks at work.
Counting down instead? Use the online timer with alarm.
Frequently asked questions
Does the stopwatch keep running if I switch tabs?
Yes. It measures real elapsed time, so it stays accurate in the background.
What are the keyboard shortcuts?
Space starts and stops, L records a lap and R resets.
Can I export lap times?
Yes. Download them as a CSV file for Excel or Google Sheets.
How precise is the stopwatch?
It displays hundredths of a second using the browser’s high-resolution clock.