Stopwatch — Precise Online Stopwatch with Lap Timer and Split Times
Our free online stopwatch provides millisecond-accurate timing using requestAnimationFrame and Date.now() delta accumulation — the most precise timing method available in web browsers. Record unlimited lap times, view split times (total elapsed at each lap), and instantly identify your best and slowest laps with green and red highlighting. Copy all lap times to the clipboard with a single click. Use keyboard shortcuts for hands-free operation.
How to Use the Stopwatch
- Click Start or press Space to begin timing. The stopwatch displays MM:SS.mm (minutes, seconds, hundredths).
- While running, click Lap or press L to record a lap time without stopping the stopwatch.
- Each lap records the lap duration (time since last lap) and the total split time.
- Click Stop or press Space to pause the timer at any point.
- While stopped, click Reset or press R to clear the timer and all laps.
- Click Copy in the laps section to copy all lap times as formatted text.
When to Use the Stopwatch
- Athletics and sports — time running laps, swimming sets, or any repetitive athletic interval.
- Fitness training — time rest periods, exercise sets, or circuit training intervals.
- Cooking — precisely time cooking stages when a simple countdown is not enough.
- Programming challenges — time your solution to competitive programming problems.
- Interviews and presentations — track timing during practice runs of presentations or interview answers.
- Science experiments — accurately measure durations in experiments and record split times.
Key Features
- Millisecond precision — requestAnimationFrame + Date.now() delta accumulation for maximum accuracy.
- Pause and resume without drift — accumulated base times prevent any time loss when pausing.
- Unlimited lap recording — record as many laps as needed.
- Split time tracking — each lap shows both the individual lap duration and the total elapsed time.
- Best lap highlighting — the fastest lap is highlighted in emerald green.
- Slowest lap highlighting — the slowest lap is highlighted in red for comparison.
- Copy lap times — one click copies all laps as "Lap N: MM:SS.mm (total: MM:SS.mm)" text.
- Keyboard shortcuts — Space to start/stop, L to lap, R to reset.
- Ring animation — the progress ring completes one revolution per minute as a visual pace indicator.
Frequently Asked Questions
How accurate is this stopwatch?
The stopwatch uses requestAnimationFrame to update the display at approximately 60fps and Date.now() to measure actual elapsed time. The timing accuracy is limited only by JavaScript's Date.now() resolution, which is typically 1ms in modern browsers (5ms in some for privacy reasons). For sub-millisecond precision, use the browser's performance.now() — a feature-request for future versions.
Can I time multiple events simultaneously?
The current stopwatch tracks a single timing session. For multiple simultaneous timers, open multiple browser tabs with the stopwatch. A multi-timer mode may be added in the future.
What is a lap vs a split?
A lap time is the duration of a specific interval (the time elapsed since the previous lap button press). A split time is the total elapsed time from the start to when that lap was recorded. Lap times show how each interval compared; split times show cumulative progress.
How do I copy lap times?
Click the Copy button in the Laps section header. All laps are copied as formatted text: "Lap 1: 01:23.45 (01:23.45)" with each lap on its own line. You can paste this directly into notes, spreadsheets, or documents.