Twenty-five minutes is the Pomodoro work block. This page is the single countdown. The full cycle lives on the Pomodoro timer. One block is one task. If you finish early, review or stop. Do not spend the leftover minutes shopping for a new task.
The five minute break after it matters. A twenty-five that runs into the next twenty-five is just an hour with extra guilt. Press space to start or pause, R to reset, and F for fullscreen. The screen can stay awake after you start, using the wake lock your browser allows. Pick the alarm before you begin. A bell, a chime, a beep, or a short digital pulse all come from the Web Audio API, so there is no sound file to wait on.
This page is the 25 minutes countdown and nothing else is running underneath it. Related lengths are linked under the guide if you want a neighbor, and the timer itself stays above the fold.
Questions
How do I run a 25 minutes timer on a projector?
Press start, then F or the fullscreen button. Classroom mode hides the writing so the digits fill the wall. The five minute break after it matters. A twenty-five that runs into the next twenty-five is just an hour with extra guilt.
What is 25 minutes actually good for?
Twenty-five minutes is the Pomodoro work block. This page is the single countdown. The full cycle lives on the Pomodoro timer.
Will the countdown drift if I switch tabs?
No. The end is a timestamp. The display is the gap between that timestamp and now, so a background tab does not lose seconds the way a ticking counter would.