Free online stopwatch with lap recording and countdown timer with audio alerts. Large display, precise to centiseconds. Free, private, runs entirely in your browser.
Accurate to centiseconds with start, stop, resume, and reset controls. Record unlimited lap times with split and total time tracking.
Set hours, minutes, and seconds for a custom countdown. Visual progress ring shows remaining time at a glance with smooth animation.
Countdown timer plays an audio alert using the Web Audio API when time is up. No audio files needed -- sound is generated in the browser.
Responsive design works on desktop, tablet, and mobile. Large display numbers are easy to read from a distance.
A stopwatch measures elapsed time from a starting point, while a countdown timer counts down from a set duration to zero. Both are essential time management tools used in sports, cooking, productivity techniques like the Pomodoro method, presentations, fitness training, and everyday tasks.
This stopwatch uses JavaScript's Date.now() method for precise time tracking. When you click Start, the current timestamp is recorded. The display updates every 10 milliseconds, calculating elapsed time as the difference between the current timestamp and the start timestamp plus any previously accumulated time. This approach ensures accuracy even when the browser tab is in the background, as the elapsed time is calculated from absolute timestamps rather than counting intervals.
The countdown timer converts your input hours, minutes, and seconds to milliseconds and tracks remaining time using the same timestamp-based approach. A circular SVG progress ring provides visual feedback on the remaining time. When the countdown reaches zero, the Web Audio API generates a series of alternating tones to alert you.
The stopwatch supports recording unlimited lap times. Each lap records both the split time (time elapsed during that specific lap) and the total elapsed time. Laps are displayed in reverse chronological order so the most recent lap is always visible at the top.
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