Interval timer for Tabata, HIIT and Pomodoro

Interval sequences: Tabata, HIIT, CrossFit, Yoga, Pomodoro

Some routines are not one duration but a chain of them, and re-setting a timer between every phase defeats the purpose. The Sequences tab lets you build a list of named steps that run back to back automatically, announcing each transition so you never have to look at the screen mid-burpee.

Ready-made workout presets

Tabata is the strictest and shortest: 20 seconds all-out, 10 seconds rest, eight rounds, four minutes total. It comes from Japanese research on speed skaters and it is genuinely brutal if you do it properly. HIIT is the looser family it belongs to — longer work intervals, longer recovery, more forgiving. CrossFit loads a circuit structure with warm-up, work blocks and rest. Yoga takes the opposite approach: long holds, gentle transitions, a calm end sound instead of a klaxon. Advanced Pomodoro builds a full work session — focus blocks, short breaks, and a longer break after the fourth cycle.

TABATA: EIGHT ROUNDS OF 20 SECONDS ON, 10 SECONDS OFF

Building your own sequence

Add steps one at a time with a name and a duration. Reorder with the ▲▼ arrows, duplicate with ⧉, delete with ✕. Duplication is the feature that saves the most time in practice: build "Exercise 40s" and "Rest 20s" once, then duplicate the pair as many times as your circuit needs, renaming as you go.

A beep sounds during the last three seconds of every phase so you can anticipate the change, and a voice announces each transition by name using your browser's speech synthesis. You keep your eyes on the exercise instead of the screen. Voice can be switched off, and the step-change sound is chosen from the same ten alarms as everywhere else.

Saving programs you will reuse

Once a sequence works, name it and save it. It stays on your device and reloads with one click, so your Monday session, your warm-up routine and your study pattern are always a tap away. Saving requires local storage to be enabled.

The presets in detail

Preset	Structure	Total
Tabata	20 s work / 10 s rest × 8	4 minutes
HIIT	40 s work / 20 s rest, longer sets	varies
CrossFit	warm-up, work blocks, rest	varies
Yoga	long holds, gentle transitions	varies
Pomodoro	25 min focus / 5 min break, long break after 4	2 hours

All five are starting points rather than prescriptions — every step can be renamed, retimed, reordered or deleted once loaded.

Where Tabata came from

The 20/10 structure is not arbitrary. It comes from research by Dr Izumi Tabata on Japanese speed skaters, comparing short maximal intervals against longer moderate sessions. The finding that made it famous was that four minutes of genuine maximal effort produced adaptations comparable to far longer steady work.

The word "maximal" is doing heavy lifting there, and it is the part usually dropped. Tabata done properly is unpleasant and leaves you unable to hold a conversation. Tabata done at a comfortable pace is simply a four-minute workout with a famous name.

Building your own sequence

Add steps one at a time with a name and a duration, then use the arrows to reorder and the duplicate button to repeat a pair. Duplication is the feature that saves the most time in practice: build "Exercise 40s" and "Rest 20s" once, duplicate the pair six times, then rename each work step with the actual movement. Sixty seconds of setup for a full circuit that announces every exercise by name while you train.

A workable structure for a home circuit: two minutes of warm-up, then six rounds of 40 seconds work and 20 seconds rest, then two minutes of stretching. Save it under a name and it reloads with one click next week.

Why interval training works

The reason short, hard intervals produce results that longer, easier sessions do not comes down to which energy systems you force the body to use.

Your muscles draw on three overlapping systems. The phosphagen system provides immediate power and is exhausted within about ten seconds. The glycolytic system takes over for efforts lasting roughly ten seconds to two minutes, producing energy quickly but generating the metabolic by-products responsible for that burning sensation. The aerobic system is slower to engage but effectively unlimited, and it powers everything beyond a couple of minutes.

Steady moderate exercise trains the aerobic system almost exclusively. Intervals recruit all three: the work period drives you deep into glycolytic territory, and the rest period forces the aerobic system to clear the by-products and restore capacity before the next round. Repeating that cycle is a far stronger stimulus than an equivalent volume of comfortable work, which is why four minutes of correctly executed Tabata is genuinely demanding.

What the work-to-rest ratio controls

The ratio between work and rest is the main dial, and it determines what kind of adaptation you get.

• 1:3 or longer rest (20 s work, 60 s rest) — near-complete recovery. Trains power and speed. You should be able to repeat the effort at full intensity.
• 1:1 (40 s work, 40 s rest) — partial recovery. Trains work capacity, the middle ground most circuits live in.
• 2:1 (40 s work, 20 s rest) — incomplete recovery. Accumulates fatigue deliberately. Demanding, and the point at which form starts to matter more than effort.
• Tabata's 2:1 (20 s work, 10 s rest) — the extreme version, sustainable only because the work periods are so short.

A common mistake is choosing a ratio that makes the session feel hard rather than one that trains what you actually want. If your goal is speed and every repetition is slower than the last, your rest is too short and you are training fatigue tolerance instead.

WHAT THE WORK-TO-REST RATIO CHANGES, DRAWN TO SCALE

Tabata: what the study actually found

The protocol comes from research led by Dr Izumi Tabata at Japan's National Institute of Fitness and Sports, published in 1996. His team compared two groups of athletes. One trained at moderate intensity for an hour, five days a week. The other did the 20/10 protocol — eight rounds, four minutes total — four days a week, with one moderate session.

After six weeks the moderate group had improved aerobic capacity but showed no change in anaerobic capacity. The interval group had improved both, with a larger aerobic gain despite training for a fraction of the time.

Two details are almost always omitted when the protocol is repeated online. First, the subjects were already well-trained athletes, not beginners. Second, and more importantly, the intervals were performed at roughly 170 % of VO₂ max — an intensity that is genuinely maximal and cannot be sustained through eight rounds without the last few being an act of will. Tabata performed at a comfortable pace is not Tabata; it is a four-minute workout with a borrowed name.

Pomodoro: the method, not just the timer

Francesco Cirillo developed the technique as a university student in the late 1980s, using a tomato-shaped kitchen timer — pomodoro is Italian for tomato. The method is more specific than the popular version suggests, and the specifics are what make it work.

A pomodoro is 25 minutes of single-task work followed by a 5-minute break, with a longer 15 to 30-minute break after every fourth. The rules that matter:

• A pomodoro is indivisible. If you break off to check a message, it does not count. Start again.
• Interruptions get written down, not acted on. When something occurs to you mid-block, note it and return to the task. Deal with the list during the break.
• The break is mandatory. Working through it defeats the purpose — the recovery is what makes the next block possible.
• Plan in pomodoros. Estimating a task as "three pomodoros" is more accurate than estimating it in hours, and the feedback loop improves your estimates fast.

Twenty-five minutes is not sacred. It is short enough that starting feels easy and long enough to reach genuine focus. If your work has a longer warm-up — writing, complex analysis, debugging — 50-minute blocks with 10-minute breaks often suit better, which is the variant loaded in the presets.

Building a program that progresses

A circuit that never changes stops producing results within a few weeks. The three variables to move, in rough order of preference:

Add rounds first. Going from six to eight rounds at the same intensity is the simplest progression and the easiest to recover from.

Then shorten the rest. Cutting rest from 30 to 20 seconds raises the demand substantially without changing anything you do.

Then extend the work. Lengthening the work period changes which energy system dominates, so treat it as a different session rather than a harder version of the same one.

Change one variable at a time and hold it for two or three weeks. Changing everything at once means you learn nothing about what worked.

A worked example: a 20-minute home circuit

Build it once, save it, reload it every week:

• Warm-up — 3 minutes
• Six rounds of: Work 40 s, Rest 20 s
• Recovery — 2 minutes
• Six rounds of: Work 40 s, Rest 20 s
• Cool down and stretch — 3 minutes

Name each work step with the actual movement — "Squats", "Push-ups", "Mountain climbers" — and the voice will call them out as they arrive. You never look at the screen, which is the difference between following a program and reading one.

Common questions