How to use
Click **Start** to begin a 25-minute focus block. When it ends the timer plays an alarm, shows a browser notification (if you granted permission), and automatically queues a 5-minute short break. After four focus blocks, the next break is a 15-minute long break. The cycle count and total completed pomodoros today persist across page reloads via localStorage, so closing the tab and reopening it keeps your session counter intact.
The 25 / 5 / 15 default reflects Francesco Cirillo's original 1980s technique, but you can adjust each interval to fit your work style: 50 / 10 (longer "ultradian" cycles favored by researchers), 90 / 20 (Tony Schwartz / NSF Stage-2 sleep research), or shorter 15 / 3 for ADHD-friendly micro-sessions. Browser tabs are throttled by Chrome and Safari when backgrounded, so the timer will fire late if you switch to another tab; we mitigate this by using Web Audio scheduled events for the alarm and computing remaining time from `Date.now()` rather than `setTimeout` deltas, so the elapsed count stays accurate even when the tab is inactive.
Examples
Standard 4-cycle workday session
Input
preset: classic (25 / 5 / 15)
start at: 09:00
goal: 4 pomodoros before lunch
Output
09:00 - 09:25 focus #1 (25 min)
09:25 - 09:30 break (5 min)
09:30 - 09:55 focus #2 (25 min)
09:55 - 10:00 break (5 min)
10:00 - 10:25 focus #3 (25 min)
10:25 - 10:30 break (5 min)
10:30 - 10:55 focus #4 (25 min)
10:55 - 11:10 long break (15 min)
Total: 1 h 55 min for 4 × 25 min focused work
A standard pre-lunch block yields just under 2 hours of focused work in slightly less than 2 hours of clock time. The structure helps because the 5-minute breaks are short enough that mental momentum survives but long enough that you can stand, drink water, or look out the window — preventing the muscular and visual fatigue of staring at a screen for 2 hours straight. The 15-minute long break is the natural lunch-prep window.
Deep-work 90 / 20 ultradian preset
Input
preset: ultradian (90 / 20)
start at: 08:00
use case: long-form writing, deep research, complex coding
Output
08:00 - 09:30 focus #1 (90 min)
09:30 - 09:50 break (20 min)
09:50 - 11:20 focus #2 (90 min)
11:20 - 11:40 break (20 min)
11:40 - 13:10 focus #3 (90 min)
13:10 - 13:30 break (20 min)
Total: 4 h 30 min focused work in 5 h 30 min
For tasks that need deep state — writing, complex coding, research synthesis — the 25-minute classic block can feel disruptive because the 5-minute interruption interrupts flow just as it stabilizes. The 90 / 20 ultradian variant aligns with Nathaniel Kleitman's research on natural human attention cycles. Trade-off: harder to find a single 90-minute distraction-free block in a typical office; better suited to remote or solo days. Cal Newport's "Deep Work" book popularized this variant.
ADHD-friendly micro-sessions
Input
preset: micro (15 / 3 / 10)
start at: 14:00
use case: task initiation, low-energy afternoons
Output
14:00 - 14:15 focus #1 (15 min)
14:15 - 14:18 break (3 min)
14:18 - 14:33 focus #2 (15 min)
14:33 - 14:36 break (3 min)
14:36 - 14:51 focus #3 (15 min)
14:51 - 14:54 break (3 min)
14:54 - 15:09 focus #4 (15 min)
15:09 - 15:19 long break (10 min)
Total: 1 h 19 min for 4 × 15 min
For people with ADHD or chronic fatigue, the 25-minute block can feel like an insurmountable starting commitment. The 15-minute variant lowers the activation threshold — "I can sit down for 15 minutes" is psychologically easier than "I need to focus for 25 minutes". Once started, many continue past the 15-minute mark naturally because momentum has kicked in. The trade-off is more frequent context switching, which is fine for task initiation but suboptimal for sustained deep work. This pattern is often recommended by ADHD coaches and was popularized by Jessica McCabe of How To ADHD.
FAQ
Where does the Pomodoro Technique come from?
Francesco Cirillo, an Italian university student, devised the technique in 1987 while studying at Università LUISS in Rome. He used a tomato-shaped (`pomodoro` in Italian) kitchen timer — hence the name — to commit himself to 10 minutes of uninterrupted study. The duration grew to 25 minutes through trial and error as Cirillo found this balanced productivity against attention fatigue. He formalized the methodology in the 1990s and self-published a book in 2006; the technique then spread widely after coverage by 43folders, Lifehacker, and software-development blogs in the late 2000s. Cirillo's company still licenses the trademark and consulting around the technique.
Why 25 minutes and not 30 or 20?
Cirillo arrived at 25 empirically — long enough to make meaningful progress on a task, short enough that the activation cost of restarting after a break stays manageable. Subsequent research has not validated 25 as a magic number; what matters is having a fixed, modest interval that creates artificial scarcity around attention. Research on sustained attention (Nathaniel Kleitman's ultradian rhythms, Karolinska Institute studies on vigilance decrement) suggests natural attention cycles range 70–120 minutes, but these refer to peak biological capacity rather than what people can comfortably sustain on knowledge work. The 25-minute size is best understood as a *commitment device* not a biological optimum — short enough that you cannot reasonably claim "I do not have time for one", which makes starting easier.
What happens if I get interrupted mid-pomodoro?
Cirillo's original rule is strict: if you get interrupted (someone walks up to your desk, an urgent Slack ping, a phone call) and cannot defer it, the pomodoro is "void" and does not count toward your daily tally. Restart the 25-minute clock from zero. This rule sounds harsh but serves a real purpose: it makes the interruption visible. After a few voided pomodoros, you start to negotiate boundaries with colleagues, silence Slack, or close your office door. The technique is partly an attention practice and partly a measurement system — voided counts surface how often you are actually interrupted, which lets you address the source rather than the symptom.
Does the timer keep running if I close the browser tab?
No — when the tab is closed the JavaScript context is destroyed and the timer cannot continue. However, this tool persists the *start time* of the active session in localStorage, so when you reopen the tool in the same browser within the original window, it resumes from the elapsed time and fires the alarm at the originally scheduled moment if you are within range. If the elapsed time has already passed the scheduled end, the tool flags the session as completed and increments the counter. Closing the tab for hours and reopening will not fire a missed alarm — that requires a Service Worker, which we deliberately omit to keep the tool simple and avoid permission prompts.
Why does my timer seem inaccurate when I switch tabs?
Browsers throttle `setTimeout` and `setInterval` in backgrounded tabs to save battery — Chrome since 2017 clamps to 1 fire per second for backgrounded tabs, and after 5 minutes drops to once per minute (or stops entirely on heavily restricted devices). A naive countdown timer that decrements a variable on each `setInterval` tick would lose time. This tool computes remaining time on each tick as `scheduledEnd - Date.now()`, so display accuracy is preserved across backgrounded tabs. The alarm itself uses Web Audio `audioContext.currentTime + offset` scheduling, which is not affected by tab throttling once scheduled. Notification delivery is sometimes delayed by the browser when the tab is hidden, but the underlying time tracking is correct.
Is the Pomodoro Technique actually evidence-based?
Mixed. The specific 25 / 5 / 15 schedule has no strong empirical backing beyond Cirillo's personal trial-and-error. However, three principles the technique embodies do have research support: **timeboxing** reduces planning fallacy and increases task completion rates (Roy Baumeister, Mark Muraven on ego depletion); **brief structured breaks** preserve cognitive performance better than continuous work (University of Illinois 2011 study by Atsunori Ariga and Alejandro Lleras); **artificial deadlines** increase motivation through Parkinson's Law dynamics (Dan Ariely's experimental work). What the research does *not* support is the universality of 25 minutes specifically. The technique works for many people because it provides structure, externalizes attention discipline, and creates measurable units of progress — not because 25 minutes is a biologically optimal window.
Related concepts
The Pomodoro Technique sits in a broader category of **timeboxing** practices — using fixed time intervals as a tool for managing attention, motivation, and the planning fallacy. Other entries in this category include **Getting Things Done (GTD)** by David Allen (organizes tasks rather than time, but pairs naturally with pomodoros), **Time Blocking** popularized by Cal Newport (longer 90-minute or multi-hour blocks dedicated to specific projects), and **52 / 17** (a DeskTime study's observed pattern from highly productive software developers — 52 minutes work, 17 minutes break). The shared idea: human attention is not a continuously available resource, and external structure does more than internal willpower to keep it focused.
The biological substrate is **ultradian rhythms** — natural cycles of arousal and rest that run shorter than circadian (24-hour) rhythms. Nathaniel Kleitman, who also discovered REM sleep in 1953, identified a Basic Rest-Activity Cycle of roughly 90–120 minutes in waking adults. EEG studies show alertness peaks and troughs on this timescale; trying to sustain focused work across multiple ultradian cycles without breaks correlates with declining accuracy and increasing subjective fatigue. The 25-minute pomodoro takes a smaller slice of the natural cycle, betting that more frequent micro-recovery beats fewer larger breaks for most knowledge work.
Three adjacent productivity ideas overlap with Pomodoro. **Flow state** (Mihaly Csikszentmihalyi) describes the deeply absorbed state where time perception distorts and performance peaks — many critics argue 25-minute interruptions disrupt flow entry, which typically takes 15–20 minutes to reach. **Attention residue** (Sophie Leroy, 2009 research) is the cognitive cost of switching tasks: even brief task switches leave traces that degrade subsequent focus, suggesting that timed *breaks* are different from *interruptions* because the break is anticipated. **Single-tasking** is the broader discipline of refusing context switches; Pomodoro is a tactical implementation that converts the abstract principle into a measurable practice. None of these frameworks replace each other — they are complementary lenses on the same underlying problem of managing finite attention in environments designed to fragment it.
