Stopwatch and timer
Stopwatch with laps and countdown with alarm
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What is Stopwatch and timer?
You get two tools in one: a stopwatch to time how long something takes, with laps, and a countdown timer that beeps when it's done.
The stopwatch shows hundredths of a second and marks your fastest and slowest laps. The timer has 1 to 60-minute presets and shows the remaining time in the tab title.
How to use it
- Choose “Stopwatch” or “Timer”.
- In the stopwatch, click “Start” and use “Lap” to save splits.
- In the timer, enter hours, minutes and seconds or click a 1, 3, 5, 10, 15, 25, 30 or 60-minute preset.
- Turn “Sound when finished” on or off.
- Use the space bar to start or stop and the V key to mark a lap.
Advantages
- Stopwatch with hundredths, laps, splits and best and worst lap.
- Timer with a sound alert and countdown in the tab title.
- Keyboard shortcuts so you can use it without a mouse.
- Free, no sign-up and no ads.
Technical details
The stopwatch measures time with performance.now(), a high-resolution monotonic clock unaffected by changes to the system time, and accumulates intervals when pausing and resuming. It's displayed as mm:ss.cc (or h:mm:ss.cc) with hundredths, and each lap stores the split and total time, highlighting the best and worst. The timer rounds up to the second, like a kitchen timer, and when it reaches zero it plays three 880 Hz beeps generated with the Web Audio API and changes the tab title to alert you.
Frequently asked questions
How do I set a 5-minute timer?
Go to “Timer”, click the “5” preset and press “Start”. When it's done you'll hear three beeps.
Does the timer ring if I switch tabs?
Yes, and the tab also shows the countdown in its title so you can see it without returning to the page.
How do I record laps with the stopwatch?
Click “Lap” or press the V key while it's running. Each lap's split and the total time are saved, and the best and worst are marked.
How accurate is the stopwatch?
It shows hundredths of a second and uses a high-resolution clock, suitable for workouts, cooking or studying.
Can I use it for the Pomodoro technique?
Yes. Use the 25-minute timer preset for each work block and the 5-minute one for breaks.
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