Stopwatch & Countdown
Online stopwatch with lap recording and countdown timer. Full screen mode, millisecond precision, pause and resume support.
Stopwatch & Countdown Timer is a browser-based precision timing tool for any scenario where you need to measure elapsed time or count down from a set duration. It works entirely in your browser — no install, no account, no data sent anywhere.
Tool interface
The tool has two modes, switched with the tabs at the top:
Stopwatch
- Start / Pause / Resume — toggle the timer at any moment
- Lap — record a split time while the stopwatch keeps running; laps appear in a table below with best (green) and worst (red) times highlighted
- Reset — stop and clear the timer and lap list
- Full screen — expand the display to fill the screen, useful for timing sessions in a gym or classroom
The status dot beneath the display shows the current state: green (running), amber (paused), grey (stopped).
Countdown Timer
- Set hours, minutes, and seconds in the input fields
- Start / Pause / Resume — countdown begins from the set duration
- Reset — returns the timer to the configured duration
- Full screen — expands the display for visibility at a distance
- When the countdown reaches zero, a flashing "Time's up!" overlay appears
Common use cases
- Fitness — time sets, rest intervals, or a full workout session
- Cooking — count down from a recipe time
- Presentations — keep a speaker to their allotted time
- Study / Pomodoro — 25-minute focus sessions with 5-minute breaks
- Sports refereeing — lap splits for running races or swimming
- Classroom — countdown a quiz or activity
FAQ
Does the timer keep running if I switch browser tabs?
Yes. The timer uses Date.now() timestamps rather than counter increments, so it continues accumulating time accurately even when the tab is in the background or the display is not updating.
How precise is the stopwatch?
The display updates every animation frame (approximately 60 times per second) and shows milliseconds to three decimal places. Accuracy depends on the browser's timer resolution, which is typically within a few milliseconds.
Can I record laps?
Yes, in Stopwatch mode. Click the Lap button while the timer is running to record a split. The table shows the lap number, the time for that lap, and the running total split time. The fastest lap is highlighted in green and the slowest in red.
What is full screen mode?
Clicking the expand icon on the timer display enters browser full screen, enlarging the digits to fill the entire screen. This is useful when the timer needs to be visible from a distance — during a workout, a classroom activity, or a presentation. Press Escape or click the button again to exit.
Does the countdown play a sound when it finishes?
Not currently. When the countdown reaches zero, a flashing "Time's up!" overlay appears on the display. Audio alerts are not available because they require user interaction permissions that vary across browsers.