45 Minute Timer
Three quarters of an hour is about as long as most people find they can hold a single task before the quality starts to slide, and it is roughly the length of a school lesson in a lot of countries. The countdown above is set to 45:00.
Pair it with a fifteen-minute break and you get a clean hour that repeats all day, which is the main reason people choose it over the shorter sprint lengths.
Set Timer
Why 45 rather than 25
Some work has a warm-up cost. Debugging something intricate, following a mathematical argument, getting back into a draft you left on Friday — the first ten minutes are spent rebuilding the state in your head, and only then does progress start. Break every 25 minutes and you pay that cost again and again; a 45-minute block pays it once and gets 35 useful minutes out of it.
Shorter blocks win for work you are avoiding, because the barrier to starting is lower. Longer blocks win for work you have already started and want to go deep on. Choose by the task, not by loyalty to a method.
Making the block hold
Forty-five minutes is long enough that interruption is the main risk. Decide the single thing before pressing “Start”, put the phone in another room rather than face-down on the desk, and keep a scrap of paper for the unrelated thoughts that will arrive — write them down, do not act on them, deal with them in the break.
Take the break properly when it sounds. A break spent in the same chair on the same screen is not a break, and by the third block you will feel the difference.
Where else 45 turns up
A baked potato in a hot oven, a lasagne settling into its top layer, a slow-proving dough on a warm day. A full gym session including warm-up. A wash cycle. A therapy hour, which has traditionally been closer to fifty minutes than sixty.
For any of these, the countdown appears in the browser tab title as it runs, so you can leave this tab in the background and still glance at how long is left.