About the Online Timer
Set a countdown timer for cooking, study sessions, exams, presentations or classroom activities. Pick a preset or type any time, press Start, and an alarm sounds when time is up.
The full-screen mode shows big digits that can be read across a room, and on phones the screen is kept awake while the timer runs, where the browser allows it.
How it works
When you press Start the timer records the exact moment it should end, then shows the difference between that moment and the current time. Browsers slow down timers in tabs you aren't looking at, sometimes to once a minute, so a timer that counted ticks would fall behind. Working from the end time means the countdown is right whenever you look, and the alarm goes off as soon as the page checks.
The alarm is a short beeping tone made by the browser's audio system, not a sound file. Pressing Start counts as permission to play sound, which browsers require.
time left = end time − now end time = start time + duration (pausing saves the time left; resuming sets a new end time)
Assumptions and limits
- The tab must stay open. Closing it, or the browser fully suspending it, stops the alarm from sounding.
- In a tab that has been in the background for more than 5 minutes, Chrome may check timers only once a minute, so the alarm can sound up to a minute late. The time shown is always right when you return; keep the tab visible when exact timing matters.
- The alarm won't be heard if the device or tab is muted.
- Times are typed as minutes (5), minutes and seconds (1:30), hours, minutes and seconds (1:02:03) or words (90s, 1h 20m). The longest timer is 100 hours.
Worked examples
A 25-minute focus session
Tap the 25 min preset and Start. Switch to other tabs as you like: the title of this tab shows the time left, and the alarm plays when the session ends.
A classroom activity on the projector
Type 12, press Start, then the full-screen button. The digits fill the screen; press Escape or the button again to exit.
Cooking that needs a little longer
When the alarm sounds and the food isn't ready, press '+1 min' to add time and Resume, without setting the timer up again.
How to use the Online Timer
- Set the time. Tap a preset or type a time.
- Start. The countdown begins; pause, add a minute or reset at any time.
- Hear the alarm. It beeps when time is up and the display turns red.
Frequently asked questions
Will the timer work if I switch tabs?
Yes. The countdown is based on the end time, so it stays correct even when the browser slows down background tabs. Keep the tab open and not muted so the alarm can play when time is up.
Why didn't I hear the alarm?
Check that the device isn't muted or in silent mode, that the tab isn't muted, and that 'Play an alarm' is ticked. Phones may also stop sound when the browser is closed or the screen is locked for a long time.
Can I use it as a full-screen classroom timer?
Yes. Press the full-screen button next to Reset and the digits grow to fill the screen. On phones and tablets the screen is kept awake while the timer runs where the browser supports it.
What time formats can I type?
A plain number is minutes, so 5 means five minutes. You can also type 1:30 for a minute and a half, 1:02:03 for an hour, two minutes and three seconds, or words such as 90s, 45 min and 1h 20m.
Does the timer keep running if I reload the page?
No. The timer lives in this page only, so reloading or closing the tab resets it. Nothing is stored on a server or sent anywhere.
Sources
This tool runs entirely in your browser. What you enter or upload stays on your device and is never sent to our servers.