Classroom Timer
A large, full-screen-friendly classroom countdown timer with a chime at zero.
What is Classroom Timer?
Timed tasks work better than open-ended ones: a visible countdown gives a class a shared sense of pace for a starter, a silent reading block or an exam section. A classroom timer needs three things — it must be readable across the room, it must not drift when the tab is in the background, and it must be easy to restart between activities.
How it works
The countdown targets a fixed moment rather than subtracting a second at a time, so the display is always “deadline minus now” and stays accurate even if the browser throttles the background tab. Pausing stores what was left, so resuming continues exactly where it stopped. The chime is synthesised in the browser with the Web Audio API, so there is no audio file to download, and it can be muted for exam conditions.
- Enter your input. Type or paste your input into the field above — the tool responds instantly.
- Review the result. Output updates live as you type. Everything runs entirely in your browser.
- Copy or download. Use the Copy button to grab the result, or Download to save it as a file.
Examples
Realistic sample
Type or paste any realistic input — the tool computes the result locally and instantly.
Common mistakes
Expecting a server round-trip
Nothing is uploaded — every tool in this category runs entirely in your browser.