Online Timer
Countdown timer with alarm, presets, full screen and +1 min. Runs in your browser.
About this online timer
This online timer counts down from any time you set, from a few seconds up to 99 hours, and rings an alarm at zero. It's for anyone who needs a clear, loud timer on a laptop or phone: teachers, cooks, students timing practice papers, or you doing a quick workout.
Pick a preset or type a time like 90s, 1:30 or 1h 20m, press Start, and get on with your task. The time left shows in the browser tab, so you can see it from another tab. Full screen turns the digits big enough to read across a room.
It keeps time from the system clock and schedules the alarm the moment you press Start, so it rings on time even while you work in another window.
Features
Presets and free typing
Twelve one-click presets from 30 seconds to 1 hour start at once. Or type hours, minutes and seconds, or a quick entry like 12m 30s.
Alarm you can test
Five sounds made in the browser (beep, digital watch, chime, bell, soft tone), a volume slider and a Test sound button. Ring once, for 10 seconds to a minute, or until you stop it.
On time in a background tab
The end time is fixed when you start, and the sound is queued on the audio clock, which keeps running when the browser throttles hidden tabs.
Time left in the tab title
The tab reads something like 04:12 Tea while it runs, so you can glance at it from anywhere in your browser.
Full screen and keep screen on
Full screen shows huge digits. Keep screen on uses the Screen Wake Lock API, where your browser supports it, so the display doesn't dim halfway through.
Add time and repeat
+1 min and +5 min work while it runs or is paused. Repeat restarts the same time automatically, handy for intervals or rotating stations.
Shareable timer links
The address updates as you set the time, for example ?m=10 or ?t=1h30m, plus an optional label. Bookmark it or send it to a class.
How to use the online timer
- 1Type hours, minutes and seconds, or pick a preset such as 5 or 10 minutes.
- 2Choose the alarm sound and volume, and press Test sound to check it.
- 3Press Start or Space. Pause, add a minute or go full screen while it runs.
When to use it
Classroom activities
Put a 10 minute timer full screen on the projector for group work. Add a label like "Reading" so everyone knows what the time is for.
Cooking
Set it, switch to your recipe tab, and the alarm still rings on time. Use Repeat for a reminder to stir every 3 minutes.
Exams and practice papers
Time a 45 minute section with Keep screen on, so a laptop doesn't sleep in the middle. For focus cycles with breaks, the Pomodoro timer runs them for you.
Workouts and stretching
Repeat a 45 second timer for planks or stations. To measure how long something takes instead, use the online stopwatch with laps.
Does an online timer keep running in another tab?
It depends on how it's built. Browsers save battery by slowing timers in tabs you can't see. Chrome, for example, runs them at most once a second in a hidden tab, and after about five minutes it can bunch them up to once a minute. A timer that counts its own ticks drifts. One that waits for a tick to check whether time is up can ring a minute late.
This timer avoids both. When you press Start it stores the exact end time and asks the browser's audio engine to play the alarm at that moment. The audio clock isn't throttled the same way, so the sound arrives on time. The display and tab title catch up the moment you look.
Two limits are worth knowing. If your computer sleeps, nothing can ring until it wakes; then the timer notices and rings straight away. And phones may stop sound from a background browser tab, so on mobile keep the page on screen with Keep screen on.
How do I set a timer for a specific time?
Click a preset to start instantly, or type into the hours, minutes and seconds boxes and press Start. The Type a time box understands a few formats:
- A plain number means minutes: 25 is 25 minutes.
- Minutes and seconds with a colon: 1:30 is 90 seconds. Three parts like 1:02:03 is hours, minutes, seconds.
- Units in any order: 90s, 2.5m, 1h 20m, 1 hour 5 minutes.
- In the address bar: ?m=10, ?s=45, ?h=2, or ?t=1h30m, plus &label=Tea for a name.
How do I make the timer full screen and stop the screen turning off?
Press Full screen or the F key. Press Esc to leave. The digits scale with your screen, so a 10 minute timer on a projector is readable from the back of a room.
Tick Keep screen on before you start. It asks the browser for a screen wake lock, which works in current Chrome, Edge, Safari and Firefox. The lock is released when you pause or close the tab. Battery saver modes can refuse it, and the page tells you if that happens.
Why use Mavros
| Mavros | Typical upload sites | |
|---|---|---|
| Alarm in a background tab | Scheduled on the audio clock at Start | Often late or silent when the tab is hidden |
| Volume and test | Slider plus Test sound | Fixed volume, no preview |
| Screen stays on | Keep screen on (Wake Lock) | Screen dims during long timers |
| Time in the tab title | Yes, with your label | Sometimes |
| Reload safe | Comes back with the right time | Starts again from zero |
| Ads and sign-up | None | Ads around the digits |
Tips
- Press Test sound before an important timer. It's the quickest way to find out your laptop is muted.
- Press Space to start and pause and R to reset. Shortcuts don't fire while you're typing in a box.
- Click Notify me once if you want a desktop notification as well as the sound. The browser only asks when you click.
- To count down to a date, like a wedding or New Year, use the countdown to a date instead. It handles days and time zones.
- Need to add up several durations, like 1:45 + 2:30? The time calculator does that math.
Questions
How do I set a timer for 10 minutes?
Click the 10 min preset and it starts straight away. You can also type 10 into the minutes box and press Start, or open the page with ?m=10 at the end of the address.
Will the alarm ring if I switch tabs or minimise the browser?
Yes, on desktop browsers. The alarm is queued on the audio clock when you press Start, so throttled background timers don't delay it. If the computer sleeps, it rings as soon as it wakes.
Why didn't I hear anything?
Most often the device volume is low or muted, or the tab is muted. Press Test sound to check. If you reloaded the page while it ran, click anywhere on it once: browsers only allow sound after you interact with a page.
Can I keep my screen from going to sleep?
Yes. Tick Keep screen on. It uses the Screen Wake Lock API, which current Chrome, Edge, Safari and Firefox support. The lock is held only while the timer runs.
What's the longest timer I can set?
99 hours, 59 minutes and 59 seconds. For anything that long, a countdown to a date and time is usually more useful, since it shows days.
Can I name the timer?
Yes. Type a label like Tea or Quiz. It shows above the digits, in the tab title and in the notification, and it's saved in the link.
Can I run several timers at once?
Open the page in more than one tab. Each tab keeps its own timer, and each tab's title shows its own time left. They share the sound settings.
Is anything sent to a server?
No. The timer runs entirely in your browser. Your settings and the running timer are saved only in this browser's local storage.