Precision Millisecond Lap Stopwatch
Multi-Timer & Productivity Sprints
Run multiple concurrent countdown timers, pomodoro focus blocks, and break reminders simultaneously with sound alerts.
Active Timers
2 ActiveFrequently Asked Questions
Learn how millisecond timing accuracy, browser-synthesized audio alarms, and multi-timer concurrency work.
How accurate is the online stopwatch?
The stopwatch uses the high-resolution performance.now() browser API, which provides sub-millisecond precision independent of system clock adjustments or battery-saving CPU throttling. Laps and split times are recorded with 10ms display resolution.
How do the timer alarms work without downloading audio files?
Audio alerts are synthesized directly in your browser using the HTML5 Web Audio API. When a timer expires, the audio context generates harmonic tones (frequencies 520Hz – 880Hz) entirely in memory, eliminating external network requests and ensuring instant playback.
Can I run multiple countdown timers at the same time?
Yes. The Multi-Timer suite allows you to create and run independent concurrent timers—such as cooking timers, study sprints, tea timers, and Pomodoro focus intervals—each with custom labels, durations, and alarm alerts.
Can I export lap times for analysis?
Yes. Click "Export Laps" on the stopwatch toolbar to download a structured CSV file containing lap numbers, split times, lap durations, and overall elapsed times for import into spreadsheet software.