Stopwatch & Timer
Precise stopwatch with lap tracking and countdown timer mode.
Press Start to begin
Lap Times
| Lap | Lap Time | Total Time |
|---|
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This tool offers two modes: a stopwatch for timing events and a countdown timer for setting a specific duration. Switch between modes using the toggle at the top.
In stopwatch mode, click Start to begin timing. The display updates in real time with millisecond precision using your browser's animation frame for smooth rendering. Click Lap to record split times without stopping the clock. Each lap shows both the individual lap duration and the cumulative total. Click Stop to pause, then Resume to continue or Reset to clear.
In timer mode, enter minutes and seconds for your countdown. Click Start and the timer counts down to zero. When it reaches zero, an audible beep plays through your speakers (generated in the browser, no file download needed). The display flashes to confirm time is up. Click Reset to set a new duration.
Use this for workouts, cooking, study sessions, presentations, sports timing, or any activity where you need precise time tracking. The lap feature is especially useful for interval training and race splits.
About Stopwatch Precision
This stopwatch uses requestAnimationFrame, the browser's native animation loop that runs at your display's refresh rate (typically 60 times per second). This gives smooth, accurate updates without the timing drift that older interval-based approaches can cause. Display precision is to the hundredth of a second (10ms), which matches what most physical stopwatches show.
For competitive timing or official records, a hardware chronograph is recommended. Browser-based stopwatches depend on your device's performance and can have small variations in display updates during heavy system load. For everyday use like workouts, cooking, and study sessions, this level of precision is more than sufficient.
Frequently Asked Questions
Does the stopwatch keep running if I switch tabs?
Yes. The stopwatch tracks elapsed time based on your system clock, not animation frames. If you switch to another tab, the display pauses visually but the time continues to accumulate. When you return, the display immediately shows the correct elapsed time. No time is lost.
How accurate is the countdown timer beep?
The beep plays as soon as the timer detects the countdown has reached zero, typically within one animation frame (about 16 milliseconds on a 60Hz display). The sound is generated using the Web Audio API directly in your browser, so it plays immediately without needing to load an audio file. Make sure your device volume is turned up to hear it.
Can I record multiple laps?
Yes. While the stopwatch is running, click the Lap button as many times as needed. Each lap records both the time since the previous lap and the total elapsed time. Laps are shown in a table below the display. The most recent lap appears at the top. There is no limit on the number of laps you can record in a single session.
What happens when the countdown reaches zero?
The timer stops automatically, plays an audible beep sound, and the display changes color to indicate time is up. You can then reset the timer to the same duration and start again, or enter a new duration. The beep uses the Web Audio API, which works on all modern browsers including mobile devices.