How to use the countdown timer
- Hours, Minutes and Seconds: type a length, or press a preset from 1 min to 1 hour. The big display always shows the time Start will count down from, and the page opens on 00:05:00.
- Press Start. The status line tells you when the timer will finish and the ring shrinks as time passes. Pause holds the time, Resume carries on, and Reset takes you back to the fields.
- Leave Play a sound when time is up ticked for an alarm that repeats for about 26 seconds until you press Dismiss and stop the sound. Press Enable notifications once for a pop-up as well.
- Press the Space bar to start or pause when the cursor is not in a field and no button has focus.
How the timer keeps time
When you press Start, the timer stores the clock time at which it should end (now plus your duration) instead of subtracting one second per tick. Four times a second it compares that end time with your device clock and shows the difference, so a late tick cannot make it run slow. The ticker runs in a Web Worker because browsers slow down ordinary timers in background tabs, as MDN's setTimeout reference explains.
Worked example
The page opens with the 5 min preset on, the display at 00:05:00 and the status "Ready. Press Start to count down from 00:05:00." Press Start at 3:00:00 PM and the status changes to "Counting down. Ends at 3:05:00 PM." If you pause at 3:02:50, the display and tab title hold 00:02:10 and the status reads "Paused with 00:02:10 left." Press Resume at 3:03:50 and the end time moves to 3:06:00 PM.
Limits and edge cases
- The longest timer is 99 hours, 59 minutes and 59 seconds. Minutes or seconds above 59 are converted when you leave the field, so 90 in Seconds becomes 0:01:30. Decimals, negatives and zero are rejected with a message next to the fields.
- The timer lives in the open tab. Closing or reloading the page cancels it, and nothing is saved.
- Browsers only play sound after you have used the page, and pressing Start counts. iPhone Safari tabs do not offer web notifications, so the notification button is hidden there.
- To count down to a calendar date use countdown to date. For repeating work and break cycles try the Pomodoro timer, for several kitchen timers at once the cooking timer, and for a time of day the alarm clock.
Frequently asked questions
Does the countdown timer keep running if I switch tabs?
Yes. It tracks the end time against your device clock and ticks from a background worker, so the display is correct when you come back and the alarm fires on time in most desktop browsers. Browsers that freeze background tabs, mostly on phones and in power-saving modes, can delay the sound, but the time left is recalculated as soon as the tab wakes.
How do I set a timer for 90 seconds or for more than an hour?
Type 90 in Seconds and the field converts it to 1 minute 30 seconds when you leave it. For long runs use Hours, up to a limit of 99 hours, 59 minutes and 59 seconds.
Will it alert me if I close the tab?
No. A web page stops running when its tab is closed, so the timer and its alarm stop with it. Keep the tab open, in the background if you like, or use your phone's clock app for timers that must survive closing the browser.
Why do I have to click Enable notifications?
Browsers only show notification pop-ups after you grant permission. Press the button once and choose Allow, and the timer can notify you when it finishes while you work in another tab. If you chose Block, change it in your browser's site settings.