Countdown Timer
Customize your countdown duration and get an alert when time's up.
Related guide
Countdown, Pomodoro and Stopwatch: Which One Still Keeps Time in a Hidden Tab
The stopwatch recomputes the elapsed time from the system clock every 20 ms, so a throttled tab cannot make it lose a second; the countdown and the Pomodoro timer count ticks instead and fall behind. Measured on the pages: a finished countdown restarts in one press while the Pomodoro timer needs two, a 200-minute focus block is accepted despite the field saying 120, and a negative entry leaves 0-5:00 on screen.
Presets and custom durations
Five presets are offered — 1 minute, 5, 10 and 30 minutes, and 1 hour — and any of them can be overridden by typing your own hours, minutes and seconds into the three fields below. Choose a preset while the timer is running and it stops first, then loads the new duration, so you never end up with a half-finished countdown you did not ask for.
The three fields accept any whole number and are only read when the timer is reset. Typing a new figure while the countdown is running changes nothing until you press Reset, which is deliberate: it means the duration you set is the duration you get, not whatever the field happened to hold when the last tick fired.
Reading the display
The large digits are minutes and seconds, with no hours field, so an hour-long preset reads 60:00 rather than 1:00:00. That is a display convention only — the underlying count is in seconds, and any duration you type is honoured exactly.
The bar underneath is the share of the countdown already spent, so it fills left to right and reaches full as the display hits zero. When it gets there the button flips back to a start state, a "Time's up" notice appears, and a short 800 Hz tone plays through your device speakers. The tone is generated in the browser rather than loaded from a file, so it works offline — but it does need your volume up and the tab not muted.
How accurate it is
The timer is accurate to one second and no finer; there are no tenths. It counts down one unit per tick rather than reading the clock each time, which is what makes it simple and also what limits it: a browser throttles timers in background tabs, and a laptop that goes to sleep stops firing them altogether. If you switch away for a long stretch or close the lid, treat the remaining time as approximate and expect it to lag behind real time.
For anything where the exact end point matters — a hard deadline, a timed exam, something with money attached — use the system clock rather than a browser tab, and keep the tab visible if you do use this one.
FAQ
How do I set two hours?
Type 2 into the hours field and press Reset. The display will read 120:00, which is the same duration — the digits simply show minutes and seconds rather than hours, minutes and seconds.
Can I pause and pick up where I left off?
Yes. Pause stops the count without losing the remaining time, and the same button resumes from exactly where it stopped. Reset is the only control that discards progress, and it re-reads the duration fields when it does.
Why did the sound not play when the time was up?
The tone is generated with the browser Web Audio API, which needs the tab unmuted and the system volume up. It can also be blocked until you have interacted with the page, so press Start with a real click rather than triggering it from a script. The visual "Time's up" notice appears regardless.
Does the countdown keep running in a background tab?
It keeps counting, but browser timer throttling and device sleep both slow it down relative to real time. The count is driven by an interval rather than by comparing against the clock, so the two can drift apart. Keep the tab visible for anything time-critical.
Can I run more than one countdown at once?
Not in the same tab — there is a single timer per page. Opening a second tab gives you a second independent countdown, which is usually the cleaner way to track two things.
Is anything about the timer sent to a server?
No. The countdown is pure browser JavaScript, and nothing you enter leaves the page. That also means reloading or closing the tab clears it — there is no saved state to come back to.