Stopwatch & Timer
Online stopwatch with lap times and countdown timer. Accurate to milliseconds. Free, private, browser-based.
Local processingWhat is Stopwatch & Timer?
A stopwatch measures elapsed time from a start point with millisecond precision. A countdown timer counts down from a set duration to zero.
How It Works
The stopwatch uses performance.now() for drift-free timing and requestAnimationFrame for smooth display updates. Lap times record the cumulative time at each lap press.
Common Use Cases
- Timing tasks and activities
- Recording lap times for sports
- Cooking and exercise timers
Technical Details
Uses performance.now() (monotonic clock, not affected by NTP adjustments) for timing. Display updates via requestAnimationFrame (~60fps). Lap storage in a React state array.
How to Use
- Click Start to begin timing
- Click Lap to record split times
- Click Stop to pause, Reset to clear
Privacy
All processing happens in your browser. Your data is never uploaded to any server.
FAQ
Is the stopwatch accurate?
Yes. It uses performance.now() for millisecond-accurate timing, unaffected by system clock adjustments.
Can I record lap times?
Yes. Click Lap to record the current split time. Each lap shows the lap duration and cumulative time.