Classroom Timer
A big, clear countdown for your class: pick a preset or type a time, put it full screen on the board, and let the color change and the alarm tell everyone when time is up.
Big full-screen countdown for the class.
How to use Classroom Timer
- Pick a preset from 1 to 30 minutes, or type your own minutes and seconds and press Set time
- Press Start (or the Space bar), then Full screen to fill the board
- Watch it turn amber near the end and red for the last 10 seconds; at zero it shows Time's up! and beeps; press Reset (or R) to start over
About Classroom Timer
Classroom Timer is a countdown made to be read from the back of the room. Choose a preset (1, 2, 3, 5, 10, 15, 20 or 30 minutes) or type your own minutes and seconds, up to 180 minutes, and press Start. The digits grow to fill whatever space they have, so they stay huge on a projector or interactive whiteboard, and the Full screen button gives the whole display to the clock. Where a browser doesn't allow full screen for web pages, such as Safari on iPhone, the timer fills the browser window instead.
Color does the warning for you. The panel turns green when the countdown starts, amber for the last 20% of the time and red for the final 10 seconds; at zero it shows "Time's up!" and plays a short alarm of three bursts of beeps. The sound is generated by your browser with the Web Audio API, so there is no audio file to load, and the Sound button turns it off for quiet work. A bar under the digits shows how much of the time is left, Space starts and pauses, and R resets while the timer is selected.
The countdown is worked out from the moment it should end rather than by counting ticks, so switching to your slides or another tab doesn't make it drift, and the tab title shows the time left. In browsers that support the Screen Wake Lock API, the screen is kept awake while the timer runs. It's free with no sign-up, there are no ads on this page, and the timer runs entirely in your browser. You can also embed the timer on a class website or learning platform page that allows iframes, using the code on this page.
Frequently asked questions
- How do I show the timer on my smartboard or projector?
- Open this page on the computer connected to the board, set the time and press Full screen. The digits scale up to fill the display, and the color, the bar and the Start button come with them. Press Esc or Exit full screen to get your page back.
- Does the timer keep time if I switch to my slides or another tab?
- Yes. The time left is calculated from the moment the countdown should end, not by counting a number down, so it can't drift while the page is in the background. Browsers slow down or pause background tabs, so the alarm may be delayed until you come back to the tab, but the countdown itself never loses time and catches up the instant you return.
- Why didn't I hear the alarm?
- Browsers only let a page make sound after you've clicked or pressed a key on it. Pressing Start or the Space bar counts, so the alarm is normally ready by the time it's needed. If you hear nothing, check that the Sound button says on, that the tab isn't muted and that the volume is up; switching Sound off and on again plays one short test beep. On iPhones and iPads, Silent mode can also mute browser sounds.
- Can I set a custom time?
- Yes. Type minutes and seconds into the Custom boxes and press Set time (or Enter). Anything from 1 second up to 180 minutes works, and extra seconds roll over, so 0 minutes and 90 seconds becomes 1:30. Times of an hour or more show the hours too, like 1:15:00.
- What do the colors mean?
- Before you start, the panel is a neutral grey. Once the timer is running it turns green, then amber for the last 20% of the time (the last minute of a 5-minute timer) and red for the final 10 seconds. At zero it stays red and shows "Time's up!", so students can read the state from across the room even with the sound off.
- Will my screen go to sleep while the timer is running?
- In browsers that support the Screen Wake Lock API, the page asks the device to keep the screen on while the timer runs, and lets it sleep again when you pause, reset or reach zero. If your browser doesn't support it, or the timer is embedded on another site, set the computer's screen sleep time longer than the countdown.
- Can I control the timer from the keyboard?
- Yes. Space starts, pauses and resumes the countdown (as long as you aren't typing in the minutes or seconds boxes), and R resets it when the timer is selected or in full screen. You can also Tab to any button and press Enter.
- Can I put the timer on my class website or learning platform?
- Yes. Copy the code from the Embed this tool box on this page and paste it where your site accepts HTML or embed code. It works on any site or learning platform that allows iframes, and the embedded timer shows no ads and sends no analytics.