A clean, fullscreen timer that every student can see from anywhere in the room. Control it from your desk.
A classroom timer only works if every student can see it. A phone on the teacher's desk or a small window on the interactive whiteboard just doesn't cut it — the kids in the back row can't tell how much time they have left.
Castimer's fullscreen timer for classroom use fills the entire screen with large, high-contrast numbers. The flip animation is visible from every seat, even in a large classroom or auditorium.
When students can see a clear countdown for students, they manage their own time better. No more “How much time is left?” every 30 seconds. No more rushing through the last two questions.
The best teacher timer is the one you can manage without leaving your desk. With Castimer, you set up the countdown on your computer or phone, and the classroom screen shows the timer in fullscreen.
Start, pause, resume, or reset the timer from your device. The classroom display updates in real time. You don't need to walk to the board, switch tabs, or use a separate controller.
For a complete guide on connecting your classroom screen, see our casting guide.
Start and stop the timer from your phone
Adjust duration without touching the board
Pause for interruptions, then resume
Reset to zero with a single tap
A classroom timer is useful for much more than timed tests. Here are the most common teaching scenarios where a visible countdown makes a difference.
Set a countdown for the quiz duration. Students can see exactly how much time remains and pace themselves. Fewer questions about how long is left.
When groups are working on projects, a large <strong>classroom timer</strong> on the board helps every team stay on track. Call time is clear to all.
Fair timing for both sides of a debate. Each speaker gets their allotted time, and the audience can see the <strong>countdown for students</strong> in real time.
Collecting homework, setting up materials, moving to the library — a short 1-2 minute countdown keeps transitions snappy and keeps the lesson flowing.
Three simple steps to add a school timer online to your next class session.
Go to the timer page and set your duration, theme, and sound. Create the countdown from your teacher laptop or phone. No software to install.
Create Timer →Open the viewer on the classroom screen or projector. Students see a large, clear countdown with a smooth flip animation. Even the back row can read it.
Open Viewer →A question comes up? Pause the timer from your desk. Activity finished early? Reset to zero instantly. The classroom display syncs in real time.
Choose the setup that matches your classroom. A projector timer or smart board display — both work great.
The most reliable method. Connect your laptop to the classroom projector with an HDMI cable. Open the viewer link in your browser and go fullscreen. The timer fills the entire projected image with no input lag.
Many modern classrooms have interactive whiteboards or large display screens. Open the viewer link directly in the board's built-in browser. The <strong>classroom timer</strong> displays fullscreen alongside your teaching materials.
If your classroom has a Chromecast device, open the viewer link in Chrome and use the browser's built-in cast feature. Right-click the page and select "Cast" to display the timer on your classroom TV wirelessly.
Whether you're teaching in a elementary classroom with a single monitor, a university lecture hall with a massive projector, or a mobile cart setup — Castimer adapts to your room.
The fullscreen timer for classroom use automatically scales to any screen resolution. On a large projector, the numbers are huge. On a smaller display, they adjust to remain readable.
The school timer online works in every major browser — Chrome, Safari, Edge, Firefox. No special software, no IT department required.
Open the viewer directly on the board browser.
HDMI or wireless — the timer scales to any resolution.
Cast wirelessly or connect via browser.
Plug in via HDMI for the most reliable display.
Quick answers about using Castimer as a classroom timer.
Yes, completely free. No signup, no download, no limits. Set up your classroom timer in seconds and start counting down.
Yes. Open the viewer link directly in the smart board's built-in web browser. The timer displays fullscreen with large, clear numbers that every student can see.
No. Everything runs in the browser. The teacher controls the timer from their device, and students simply look at the classroom screen. No apps, no accounts needed.
A classroom timer is designed for a teacher controlling the countdown while students watch from a distance. A meeting timer is built for multiple participants discussing different agenda items. See our Meeting Timer page for team meeting use cases.
Free. No signup. Perfect for quizzes, group work, and presentations.