Countdown Timer
Set a duration and count down to zero, with a fullscreen display for events, speakers and classrooms.
Need a dedicated setup? Meeting Timer, Presentation Timer, Classroom Timer, Study Timer.
Options
Leave a field blank to disable that warning.
05:00
Set a duration and press Start.
For the best chance of hearing the alert, keep this tab open and active, keep the device awake, and ensure sound is allowed. Backgrounding the tab may delay or prevent the alert.
Keyboard shortcuts
- Space — Start, pause or resume
- R — Restart from the full duration
- F — Enter or exit fullscreen
- M — Mute or unmute the alert
How this timer works
Enter hours, minutes and seconds — or pick a preset — then press Start to count down to zero. Pause freezes the remaining time exactly where it stood, and Resume continues from there.
The duration fields lock once you start, since changing them mid-countdown would make the remaining time jump. Restart immediately starts a fresh countdown from the same duration; Reset stops and unlocks the fields so you can set a different one.
When the countdown reaches zero, the display clearly reads "Time's up" and, unless muted, plays a short audible alert. Nothing plays automatically on page load — sound has to be unlocked by a real interaction first, and exactly how that happens depends on how the timer was started. For a timer you set up and start yourself, pressing Start is that interaction, and the Mute toggle is visible before you do. Opening a shared live timer link is different: it starts counting down the instant you open it, without you pressing anything, so sound is NOT unlocked automatically in that case — an Enable sound control appears until you click it, and only then can the alert actually play.
Fullscreen mode enlarges the display for a room: speakers, meetings, classrooms and workshops. It uses your browser's fullscreen feature where available; if that isn't supported, the large-display view still works without going edge-to-edge.
This page has to stay open, active and unthrottled to reliably alert you, and what happens otherwise depends on which of three things you do. Merely backgrounding or minimizing an open tab is the mildest case: the display stops updating while hidden, but the countdown's own clock keeps advancing, so remaining time normally recalculates correctly the moment you return — the audible alert doesn't get the same free pass, since browsers may suspend or throttle it enough to play it late, only on return, or not at all. A sleeping or locked device is less predictable still: whether time is tracked accurately or the alert fires while asleep depends on the browser and operating system, not this page. Closing or reloading the tab is different again, not just less reliable — nothing is retained, so the countdown itself is cancelled outright: the duration, remaining time and any timer setup are gone, and closing or reloading the tab always resets it. Your fullscreen theme and size choice are the one thing saved, in your browser's local storage, so that preference carries over to your next visit.
Frequently asked questions
Does the alert sound automatically when the page loads?
No — nothing plays automatically on page load, either way. For a timer you start yourself, pressing Start is what unlocks sound (browsers require a real interaction before allowing audio), and you can mute it beforehand with the visible Mute toggle. Opening a shared live timer link is different: the countdown starts automatically without you pressing anything, but that alone doesn't unlock sound — an Enable sound button appears until you click it, and the alert stays silent until you do.
Can I change the duration while it's counting down?
Not directly — the hours/minutes/seconds fields lock once you start, so the remaining time stays consistent. Use Reset to stop and unlock the fields for a new duration, or Restart to run the same duration again from the top.
What's the difference between Restart and Reset?
Restart immediately begins a fresh countdown from the same duration and keeps running — the fast option for going again. Reset stops and returns to the setup screen with the duration fields editable again.
Does it stop or repeat at zero?
It stops. The display holds at "Time's up" until you press Restart or Reset — it does not loop or count into negative time.
Does switching tabs, minimizing the browser, or the device sleeping affect this timer?
Yes, and it depends on which of those three things happens — they're not the same. If the tab merely goes to the background or is minimized while staying open, on-screen updates pause (the display doesn't repaint while hidden), but the countdown keeps advancing against a monotonic timestamp, not a repeating tick — when you return, the remaining time normally recalculates correctly and the display catches straight up. The audible alert doesn't get the same free pass: the browser may suspend or throttle it enough that it plays late, only once you're back, or not at all. Device sleep or a locked screen is a different, less predictable case: neither that catch-up nor the alert firing at all is guaranteed there, since what actually happens to a paused browser tab across a real system sleep depends on the browser and operating system, not this page. Closing or reloading the tab or browser is different again, not just less reliable — nothing about this timer is saved, so the countdown itself is cancelled, not paused: there's no state left to catch up and no alert that can fire. For the best chance of hearing the alert, keep this tab open and active, keep the device awake, and ensure sound is allowed. Backgrounding the tab may delay or prevent the alert.
What if my device fully goes to sleep, like closing a laptop lid?
That's different from switching tabs and isn't guaranteed. A full system sleep can pause the browser entirely, and how much of that time (if any) is reflected when it wakes depends on your operating system and browser, not this page. If accurate timing across a real sleep matters, keep the device awake — fullscreen mode's wake lock helps where it's supported, but check the on-page note, since it isn't available everywhere and is a convenience, not a guarantee.
Can I use this as a stopwatch instead?
Not directly — this tool counts down to zero from a set duration. Use the Stopwatch for open-ended count-up timing with laps.
Is the countdown saved if I close the page?
The countdown itself is not — closing or reloading the page always resets it. Only your fullscreen theme and size choice is saved, in your browser's local storage, so that one preference carries over between visits.
Can I set this to go off at a specific time, like 7 AM?
Not directly — this tool counts down a duration you enter (like 25 minutes), not a specific clock time. Use the Online Alarm Clock to set an alarm for a specific time of day instead.