25 minute timer

Why this timer does not drift

Most browser timers count their own ticks: they add a second, wait, add another. A browser stops handing out those ticks to a tab you are not looking at, so the count falls behind, and a five minute timer set before you switched tabs can finish a minute late.

This one stores the instant it is due to end and works out everything on screen from your device clock. A missed tick shows a late frame; it never produces a wrong time. The tick itself comes from a background worker, which keeps running while the tab is hidden, so the alert arrives when it should rather than when the tab is next looked at.

Sound is a separate matter, and browsers are strict about it. Audio is only ever armed when you press start, never on page load, and if the browser refuses the page says so and shows the alert on screen instead. The timer works with the sound off.

The Pomodoro method, briefly

Francesco Cirillo's method is twenty-five minutes of single-task work followed by a five minute break, repeated. After four rounds you take a longer break of fifteen to thirty minutes. The length is not magic: it is short enough that starting feels cheap and long enough to get past the first few distracted minutes.

The Pomodoro timer runs the work and break phases in sequence and loops until you stop it.

Timers in a classroom

Full screen mode gives a readout legible from the back of a room, with no cursor, no chrome and no advertising. The space bar starts and pauses it and R resets it, so it can be run from a keyboard at the front without hunting for a button. The screen is kept awake while a timer runs, where the browser allows it.

Other timers

• 10 second timer Plank holds, sprint starts and the pause before a photo.
• 15 second timer Hand washing, breath holds and short drills.
• 20 second timer The rest interval in a 40/20 high intensity set.
• 30 second timer Interval training, elevator pitches and holding a stretch.
• 45 second timer The work interval in a 45/15 circuit.
• 1 minute timer Timed reading, plank tests and steeping green tea.
• 2 minute timer Brushing teeth, black tea and a warm-up round.
• 3 minute timer A soft boiled egg, a boxing round and a song.
• 4 minute timer Tabata sets and a French press.
• 5 minute timer A hard boiled egg, a short break and a classroom transition.
• 6 minute timer A firm boiled egg and a short meditation.
• 7 minute timer The seven minute workout.
• 8 minute timer Rested pasta and a group activity round.
• 10 minute timer A break, a timed test section, a rested steak.
• 12 minute timer A run interval and a batch in the oven.
• 15 minute timer A quarter hour block, a nap and a proving loaf.
• 20 minute timer A power nap, a study block and a lesson segment.
• 30 minute timer A half hour block, a workout and a slow roast stage.
• 40 minute timer The work interval in a 40/20 set, and a lesson.
• 45 minute timer A school period and a long focus block.
• 50 minute timer A university lecture and a deep work block.
• 90 minute timer One full sleep cycle and a long study block.
• 1 hour timer An exam paper, a meeting, a parking bay and a long roast.
• Pomodoro Timer Twenty-five minutes of work, five minutes of rest, on a loop.
• Stopwatch Counting up, with laps and lap statistics.
• Alarm clock Set a time of day rather than a length of time.

Timing is taken from your device clock. Accuracy is the accuracy of that clock: a machine synced to a network time server is typically within a few tens of milliseconds, and one that has not synced for a while can be seconds out. Nothing here is sent to a server.