Stopwatch & Countdown Timer

Precision stopwatch with lap recording and countdown timer with alarm — all running in your browser.

Stopwatch + Countdown Runs in browser
00:00:00
.000
READY
Lap Times
No laps recorded yet.

Keyboard Shortcuts

SpaceStart / Stop
LRecord Lap (Stopwatch)
RReset

How to use?

  1. 1
    Choose a modeSelect Stopwatch to measure elapsed time with laps, or Countdown to set a target duration.
  2. 2
    Start timingPress Start (or Space bar) to begin. Press Stop to pause and Resume to continue.
  3. 3
    Use laps or alarmIn Stopwatch mode, press Lap to record split times. In Countdown mode an alarm sounds and the screen flashes when time runs out.

FAQ

Is the stopwatch accurate?
The timer uses the browser's high-resolution performance.now() API, offering sub-millisecond precision. Browser tab throttling when the tab is in the background may slightly affect accuracy.
How many laps can I record?
There is no hard limit. All lap times are displayed in a scrollable table with split and cumulative times.
Does the countdown alarm work in a background tab?
The alarm uses the Web Audio API and plays immediately when time runs out. Most browsers throttle timers in background tabs, so keep the tab visible for critical countdowns.

Online Stopwatch & Countdown Timer — How It Works

This tool runs entirely in your browser with no installation required. The stopwatch uses performance.now() for sub-millisecond precision, while the countdown timer fires an audio alarm via the Web Audio API when it reaches zero.

Stopwatch Features

  • Start, stop, and reset with a single click or the Space bar
  • Record unlimited lap times — each row shows split and cumulative time
  • Fastest and slowest laps are highlighted automatically

Countdown Timer Features

  • Set hours, minutes, and seconds freely
  • Pause and resume at any point
  • Audible beep and screen flash when time expires

Common Use Cases

  • Sports and fitness: interval training, rest periods, race timing
  • Productivity: Pomodoro sessions, meeting timers
  • Cooking: boiling eggs, baking, steeping tea
  • Games and quizzes: time-pressure rounds

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