The Tabata protocol is unforgiving about timing and that is the whole point: the work interval has to end when it ends, not when you notice it ended. A timer that needs a glance every ten seconds has already broken the set, because looking down costs you a rep and the position of your hips.
cronoWiz calls the phases out loud, counts the last five seconds before each bell, and keeps the round number where you can read it from the floor. You build the preset once and it is there next time, on the same device, without an account attached to it.
It runs in the browser and installs as an app if you want it to. After the first load the timer works with no connection at all — useful in a garage, a basement gym, or anywhere the signal gives up.
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Voice cues, not just a beep
the phase change is announced, so the phone can stay on the floor face down.
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The preset survives
work, rest, rounds and warm-up are saved on the device and reload as you left them.
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Works with no signal
after the first load nothing is fetched. Airplane mode changes nothing.
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It ends up in the diary
a finished session is recorded with duration and effort, if you want it kept.
What the four minutes are actually for
The protocol comes from a 1996 study by Izumi Tabata on the Japanese speed-skating team: six weeks of eight rounds at roughly 170% of VO2max on a cycle ergometer, four times a week. That last number is the part usually left out. At 170% of VO2max you are not working hard, you are working at an intensity you cannot hold for the full twenty seconds by round six — which is the entire point, and the reason the original subjects did it on a bike where the resistance made cheating impossible.
Most of what gets called Tabata in a gym is a 20/10 circuit at a sustainable effort. That is a perfectly good conditioning block; it just is not the protocol, and it will not produce the study’s results. Knowing which one you are doing matters mainly for where you put it: the real thing is a standalone session with a long warm-up and nothing after it, while the 20/10 circuit slots in as a finisher.
In practice: use it twice a week at most, never on consecutive days, and pick one movement you can perform badly without hurting yourself — assault bike, rower, or air squats. The one thing to avoid is a technical lift, because round seven is where form goes and a barbell does not forgive that.
Setting it up so you never look at the screen
Build the preset once: two minutes of warm-up, twenty seconds of work, ten of rest, eight rounds. Turn voice cues on and set the volume before you start, not during — the useful test is whether you can hear the phase change from the far end of the mat with your own breathing in the way.
Then put the phone face down on the floor. cronoWiz announces every phase change, counts the last five seconds before each bell, and calls the round number, so the screen stops being something you need. If you are training with music, the cues duck the audio rather than competing with it.
If you lose count anyway, the round number is spoken at every change, so the next cue puts you back. The session lands in the diary with its duration and effort when you finish, and the preset comes back exactly as you left it next time — on that device, without an account holding it.
Free. Private. Yours.
No account. No server. No cookies. Just you, your phone, and an app that minds its own business. cronoWiz is a free PWA that runs entirely on your device — your data never leaves. Ever.
The questions people actually ask
Is four minutes really enough?
For the protocol itself, yes — that is what Tabata is. It is a finisher or a dense block, not a whole session: most people put it after strength work or at the end of an easy run.
Can I change work and rest?
Yes. 20/10 is the default because it is the classic ratio, but every value is editable and the modified preset is saved like any other.
Does it keep running with the screen off?
Yes. The timer keeps counting and the voice cues keep firing with the screen locked, which is the only way it is usable when the phone is on the floor.
Do I need an account?
No. There is no sign-up anywhere in cronoWiz. The preset lives in your browser storage, not in a profile on someone else’s server.