How long should a pomodoro focus session be?

You’ve heard “25 minutes on, 5 minutes off” so many times it sounds like physics. It’s not. It’s one person’s preference that happened to spread. The right session length depends on what you’re doing and how your attention actually behaves.

Here’s what the research actually says.

Two paths

The classic 25/5 (Cirillo’s original)

Francesco Cirillo invented the Pomodoro Technique in the late 1980s as a university student. Twenty-five minutes was simply the duration of his tomato-shaped kitchen timer — there’s no neuroscience claim under it. The technique works because of the structure, not the number: a fixed window, a single task, a short rest.

Where 25/5 shines: shallow but interruptible work — email, code reviews, admin, writing first drafts when you’re not yet warmed up. It’s a low-stakes commitment. Anyone can promise themselves 25 minutes.

Longer blocks (50/10 and 90/20)

Research on ultradian rhythms — work by Nathan Kleitman in the 1960s, expanded later by Peretz Lavie — suggests the brain cycles through roughly 90-minute peaks of alertness, separated by 20-minute troughs. Many people who do deep work (writers, designers, programmers) find 50/10 or 90/20 fits this rhythm better than 25/5.

The trade-off is honest: longer blocks demand more activation energy to start, and they’re harder to recover from if interrupted. If you can’t reliably get 30 minutes of uninterrupted time, 25/5 will produce more work than 90/20 ever will.

1. Try 25/5 for a week if you're new, or if your work is reactive.
2. If you finish most sessions wanting more, move to 50/10.
3. For deep creative work on uninterrupted mornings, try 90/20.
4. In Tempo, open Settings > Presets — the three classic lengths are built in, and you can save your own.
5. Switch presets from the menubar panel without touching settings.

Tempo doesn’t have an opinion. It just makes switching cheap, so you can run the experiment on yourself. After a week of data in the weekly view, the right length usually picks itself.