Tabata at its real 20/10/8, EMOM, or your own work and rest. The countdown is sized to be read from across a room, it keeps correct time even if the tab goes to the background, and it installs nothing.
How this timer works
The session is planned before it starts. Your preset, work, rest and round count are expanded into an explicit list of phases — an optional lead-in, then work and rest alternating for the number of rounds you asked for — so the readout can state the true total before you begin rather than discovering it as it goes. Tabata is shipped at its actual protocol, 20 seconds of work and 10 of rest over eight rounds, because Tabata is a specific study's numbers and not a general word for interval training. EMOM ships with a rest of zero, because in EMOM the rest is not a phase at all: it is whatever is left of your minute after the work is done.
The clock reads elapsed wall-clock time on every frame rather than counting timer ticks. That distinction is the whole accuracy story. A browser throttles timers in a background tab to roughly once a second, sometimes far less, so a timer built by counting its own ticks quietly runs slow — you can finish a twenty-minute session having actually trained for seventeen, with the round count insisting otherwise. Reading the difference between two timestamps means a throttled tab simply catches up the instant it is visible again, and the phase you are in stays correct. Audio is the exception: a background tab will not reliably play the cue on time, so keep the tab visible if you are going by sound.
The honest limits. This is a timer, not a coach — it does not know whether you finished the work, and it counts rounds whether or not anything happened in them. The audio cue depends on the browser allowing sound after your first interaction, so the first press is what unlocks it; if a tone never arrives, the visible phase change is the fallback and the cue can be switched off entirely. And there is deliberately no flashing at transitions: an interval timer is watched continuously by someone under exertion, which is precisely the situation a photosensitivity warning exists for, so the colours are held states rather than strobes.
Frequently asked questions
Whats the difference between Tabata and EMOM?
Tabata is a specific protocol, not a general word for interval training: 20 seconds of work, 10 seconds of rest, eight rounds, four minutes total. Those numbers come from the original study and the preset here uses them exactly. EMOM means every minute on the minute — a 60-second round where you do the work and rest in whatever is left, so the rest period shrinks as you tire. That is why the EMOM preset ships with a rest of zero: the rest is not a separate phase, it is the remainder of your minute.
Will it still be accurate if I switch tabs?
Yes. Browsers throttle timers in a background tab to once a second or less, so a timer that counts its own ticks silently runs slow — you can finish a twenty-minute session having actually done seventeen. This one reads elapsed wall-clock time on every frame instead of counting ticks, so a throttled tab catches up the moment you come back to it and the round count stays true. The one thing a background tab will not do reliably is play the audio cue on time, so if you are relying on sound, keep the tab visible.
Can I put it on a projector or a TV?
That is what the fullscreen button is for: it takes the countdown alone fullscreen, at a size meant to be read from the back of a room, and leaves the controls behind. Press Escape or tap the screen to come back — there is always a touch-accessible way out, because a fullscreen timer you cannot exit on a tablet is worse than no fullscreen at all. If your browser does not support the fullscreen API the button is hidden rather than left there to do nothing.
Does it beep, and can I turn that off?
It plays a short tone at each transition, pitched differently for work, rest and finish, so you can tell which change happened without looking up. Uncheck the cue and it runs silent. There is deliberately no flashing: an interval timer is watched continuously by someone under exertion, and a full-screen colour flash at every transition is exactly the pattern that photosensitivity warnings exist for. The colours here are held states, not strobes.
Is anything uploaded or stored?
No. The timer runs entirely in this tab, nothing is sent anywhere, there is no account, and no settings are saved — reload and it is back to the defaults. Closing the tab is all the cleanup there is.