Countdown Timer

The Countdown Timer counts down from a duration you set to zero, displaying the remaining hours, minutes, and seconds in real time and alerting you when it reaches the end. You enter a length such as 25 minutes or pick a target time, press start, and the display ticks down live in your browser, typically with start, pause, and reset controls.

The timer runs client-side using the browser's clock, updating the on-screen value roughly once per second through a JavaScript interval. Because it is anchored to a target end timestamp rather than naively decrementing a counter, it stays accurate even if your tab is throttled in the background, and many versions play a sound or flash a notification when zero is reached.

Typical uses include cooking, workouts and HIIT intervals, the Pomodoro study technique, timed exams, presentations, and keeping meetings on schedule. Event organizers also embed countdowns to product launches or deadlines. Unlike a stopwatch, which counts up to measure elapsed time, a countdown is about a fixed budget of time you do not want to exceed.

For best results, allow browser notification or sound permissions so the alert actually fires, and keep the tab open since closing it stops the timer. If you instead need to know how much time is left until a specific date and time, a date-based countdown is more appropriate, and the Time Calculator can help you work out how long an interval will be before you start the timer.