Countdown Timer

What is a countdown timer?

A countdown timer counts down from a set amount of time — five minutes, ninety seconds, an hour and a half — to zero, then sounds an alarm. That’s different from counting down to a fixed calendar date, like a wedding or a product launch; this page is the duration kind. If you’re after the date kind, our days until calculator counts down to a specific day instead.

Type a duration into the field, press start, and the timer takes it from there. There’s nothing to install and no account to create — it’s an online timer that runs the moment the page loads.

How to set a timer

1. Enter a duration. Type a number for minutes — “5” starts a 5 minute timer — or use a colon like a stopwatch, where “1:30” is ninety seconds and “1:30:00” is ninety minutes. You can also spell out units in any order, long or short form: “1h 30m”, “1 hour 30 minutes”, “30s 5m”. Or skip typing entirely and tap one of the preset buttons for 1, 5, 10, 15, 25 or 60 minutes.
2. Press Start. The display switches to counting down and the progress bar begins filling in as time passes. Pause freezes the clock exactly where it is; pressing Start again picks up right from there, and Reset returns the display to the duration you entered.
3. Let the alarm sound when it hits zero. The display counts down to 0:00 and an alarm plays. Toggle the sound icon before starting if you'd rather the timer finished silently.

Why this timer keeps time in a background tab

Most countdown timers are built the obvious way: tick once a second, subtract one from a counter. That's also how they go wrong. Browsers are allowed to slow down timers running in a tab you've switched away from — the HTML specification permits it outright, and in practice a background tab can drop to roughly one tick a minute. A timer built on ticks has no way to know that happened. It just keeps subtracting one per tick, so by the time you switch back, it has quietly lost however many ticks were skipped and is showing a confident, wrong number.

This timer works differently. The moment you press Start, it calculates the exact clock time the countdown is due to finish and stores that single moment. Every tick, however late it arrives, simply asks how far away that moment is now and displays the answer. Whether the browser ticks once a second or once a minute changes how smoothly the display updates; it never changes what the display says. We tested this against a deliberately uneven sequence of ticks, including a four-minute gap, and the countdown still landed on the correct time to the second.

What the timer accepts, and what people use it for

The input reads a handful of formats so there's no single syntax to remember. A bare number means minutes, because “a timer for 5” means five minutes to everyone who types it. A colon follows stopwatch convention, so “1:30” is ninety seconds and “1:30:00” is ninety minutes. Units work spelled out, in long or short form, in any order — “1 hour 30 minutes”, “1h 30m” and “30s 5m” all parse the same way. Anything it can't read is refused rather than quietly treated as zero, so a typo can't start a timer for no time at all. The longest duration it can show is 99:59:59, which is as far as the display goes without starting to truncate.

The display also rounds up rather than down: a 5 minute timer reads 5:00 the instant you start it rather than flicking straight to 4:59, and it only shows zero once the time is genuinely up. That makes it useful for anything measured in a fixed stretch — five minutes for tea steeping, twenty-five for a focus interval between breaks, sixty for a workout circuit or a load of laundry, or any custom length in between for a recipe step.

The alarm itself is synthesised by the browser's own audio engine rather than played from a sound file, so there's nothing to download and no delay waiting for audio to load. It only works because you pressed Start: browsers require a user interaction on the page before they'll let it make noise, and clicking Start is that interaction, so the alarm is guaranteed to have permission to sound when the countdown ends.

Why is it free?

Every second of this timer runs on your own device. The countdown, the display and the alarm sound are all generated in your browser — there's no file to fetch and no server involved once the page has loaded, so there's nothing for us to pay for by letting you use it. That's also why nothing you type here is ever sent anywhere.

No sign-up, no account, and no watermark on anything: there's genuinely nothing on the other end that needs paying for.