Online Countdown Timer with Alarm

Online countdown timer

Set it, start it and get on with your task. This free countdown timer counts down from any time you choose — from a few seconds up to 99 hours — and rings an alarm when time's up. Use the quick presets for common durations, go full screen for big readable digits during exams, presentations or workouts, and pick from four alarm sounds. It runs in your browser with no app to install.

How to use it

Tap a preset or enter hours, minutes and seconds.
Press Start. Pause and resume any time; Reset to start over.
When the alarm rings, tap Stop.

Ideas

Time a 3-hour board exam practice paper, a 2-minute tooth-brushing routine for kids, a 15-minute power nap, or perfectly boiled eggs (about 9 minutes). For focused study sessions with breaks, try thePomodoro timer; to time laps, use thestopwatch; and to wake up at a set time, theonline alarm clock.

Frequently asked questions

Will the timer keep running if I switch tabs?

Yes. The timer is based on the clock, not on counting ticks, so it stays accurate even if your browser slows down background tabs. The alarm plays when time is up as long as the page is still open.

Why didn’t I hear the alarm?

Check that your phone isn’t on silent and the volume is up. Browsers only allow sound after you tap something on the page, so always start the timer with the Start button. Keep the page open — closing the tab stops the timer.

Can I use it full screen?

Yes — tap Full screen to show just the countdown in large digits, ideal for exams, presentations, cooking or workouts. Your screen is kept awake while the timer runs, on browsers that support it.

Can I set a timer for hours?

Yes. Enter hours, minutes and seconds — up to 99 hours.