Where 25 and 5 came from, and why they are not sacred
The technique was written up in the late 1980s by Francesco Cirillo, who used a kitchen timer shaped like a tomato — pomodoro — while studying. Twenty-five minutes was what his timer conveniently measured, not the output of any study of attention. The parts that actually do work are structural: a fixed block with a defined end, a deliberate stop, and a count of completed blocks that makes the day's work visible.
So change the numbers to fit the work. Deep problem-solving that takes fifteen minutes to load into your head is badly served by a 25-minute block; 45 or 50 with a 10-minute break suits it better. Shallow, interruptible work — email, admin, small errands around a shop — runs fine at 25 or even shorter. What matters is that the length is decided before you start and does not move while you are in it.
The break is the mechanism, not the reward
The most common way to get nothing out of this is to treat breaks as optional and skip them whenever the work is going well. That converts the technique into an ordinary long working session with a timer running, which is what it was designed to replace. The break exists so that the focus block can be genuinely undivided: everything that occurs to you during the block gets written on a list and dealt with in the break, which is only possible if the break reliably arrives.
The other common failure is spending the break somewhere that does not release attention. Five minutes of scrolling leaves you no less loaded than when you stopped. Standing up, walking, water, looking at something more than a few feet away — the physical ones work better and cost nothing.
Interruptions
Cirillo's original rule is worth keeping: a focus block is indivisible. If something interrupts you, either it can wait — write it down, continue — or it cannot, in which case the block is void and you restart it rather than resuming. That sounds severe, and it is the part that changes behaviour, because a void block is a visible cost and it makes you defend the next one.
In practice a mixed rule works for most people: internal interruptions (a thought, a thing you remembered) always go on the list, and external ones (a person, a phone call) void the block if you actually engage with them. The set dots in this timer only fill on completed blocks, which is the point of counting them.
What this timer does and does not do
| Behaviour | How it works here |
|---|---|
| Tab title | Shows the remaining time so a background tab still tells you |
| Chime | Three short tones, generated in the page, needs one click first |
| Auto-advance | Optional; off means each phase waits for you to press start |
| Skip | Ends the phase now and moves to the next one in the cycle |
| Backgrounded tab | Time is measured from the clock, so throttling does not lose seconds |
| Closing the tab | Everything is lost; there is no history and nothing is stored |
That last row is deliberate rather than a limitation to be apologised for. A focus timer that logs your sessions is a different product with different privacy implications, and if you want the record, a line in a notebook at the end of the day is more useful than a chart nobody reads.
Questions people ask
Does the timer keep running if I switch tabs?
Yes. Each tick compares against the system clock rather than counting intervals, so a background tab that the browser throttles still shows the correct remaining time when you come back and the phase still ends on schedule. The tab title updates too, so a glance at the tab bar tells you where you are. Closing the tab or reloading the page ends everything.
Why did the chime not play?
Browsers block audio until the page has been interacted with, so the first chime only works after you have pressed Start at least once. If it is still silent after that, check that the sound option is ticked, that the tab is not muted in the browser tab bar, and that system volume is up. The tone is generated in the page rather than loaded as a file, so nothing is downloaded and there is nothing to fail to load.
What should I do if I finish the task before the timer does?
The classical answer is to keep working within the same topic until the block ends — review what you just did, tidy up the loose ends, plan the next block. That preserves the discipline of the fixed interval, which is what makes the count meaningful. The pragmatic answer is that if there is genuinely nothing left, take the break early and start the next block fresh rather than sitting and watching the clock.
How many focus blocks should I plan for a day?
Fewer than you think. Eight to twelve blocks of genuine undivided focus is a full and demanding day for most people, and four to six is a realistic target when the day also contains meetings and interruptions. Planning sixteen and hitting seven teaches you nothing except to distrust the plan. Count what you actually complete for a week first, then plan against that number.