space start/pause · r reset · f fullscreen
A 45 minute revision block is long enough to get through a real chunk of material and short enough to repeat three or four times in an evening. Put one topic in front of you and let the clock decide when you move on.
Open this page and press Start, or hit the space bar - the countdown is already loaded with 45 minutes. Press F for fullscreen if you want to read it from across the room, and use the custom field to switch to any other duration.
Yes. The countdown is calculated from a fixed end time rather than counted tick by tick, so background throttling cannot make it drift. The remaining time also appears in the browser tab title while you work in another tab.
Yes, it chimes three times and the clock turns red. The last ten seconds blink as a warning, and the chime can be muted with the speaker button.
Yes, it is completely free, needs no account, and runs entirely in your browser - nothing is sent to a server.