About Chalk Timer

Chalk Timer is a small set of free online timers: a shrinking ring, large digits and an alarm when time is up. It was built because most timer sites are slow, cluttered or hard to read from across a room. Each timer page opens ready to start, with no sign-up and nothing to install.

How the timer works

When you press Start, the page records the moment the countdown should end and redraws the ring and digits from that deadline. Because it counts toward a fixed end time instead of adding up seconds, the display stays accurate even if your browser slows the page down for a while. The alarm sound is generated in your browser with the Web Audio API, so no audio files are downloaded.

If you reload the page while a timer is running, it picks up where it left off. Browsers only allow sound after you interact with the page, so after a reload you may need to tap once to re-enable the alarm.

Limits on phones and tablets

A web page cannot behave exactly like a built-in clock app. On iPhone and iPad in particular, Safari may pause a page whose tab is not visible or whose screen has turned off, and the alarm will not sound until you return to it. For a timer you can rely on, keep this tab open and the screen on. Where the browser supports it, the timer asks the device to keep the screen awake while it runs. The iPhone silent switch can also mute web audio.

Questions or feedback

Found a bug or want a timer length that is missing? Send a note through the contact page.