Tabata Timer: Free Online 20/10 Interval Timer

Press Start for a classic Tabata, or shape your own session in a few seconds. Your settings are saved on this device for next time, and if you searched for a cronometro Tabata online, this is the same thing: a free interval stopwatch that runs in any browser with no app to install.

During a set, the ring around the clock fills green for work and red for rest, so one glance tells you how many rounds are left. Set rests glow yellow, and the last three seconds before every work interval count down with short beeps so you’re never caught off guard.

Tabata is a form of high-intensity interval training built on a simple rhythm: 20 seconds of maximum effort followed by 10 seconds of rest, repeated eight times. One full Tabata takes four minutes, yet done properly it is one of the hardest four minutes in fitness. Because it’s so short, it slots easily into a busy day or onto the end of a strength session.

The key word is maximum. The rest is deliberately too short for full recovery, so each round starts with your heart rate higher than the last. By rounds six to eight you should be fighting to hold your output. If you could still chat comfortably, the intensity isn’t there yet.

Tabata vs. regular HIIT

Tabata is one specific HIIT protocol. General HIIT can use any work-to-rest ratio, such as 30 seconds on and 30 off, or 40 on and 20 off. This timer handles both: keep the 20/10 default for a true Tabata, or move the sliders for any other interval format.

The stats under the timer work as a Tabata time calculator, updating total, work and rest time as you move the sliders. Here’s the math behind it, so you can plan a session before you start.

The timer finishes on your final work interval instead of waiting through one last 10-second rest, so a classic Tabata shows 3:50 of training plus your countdown. Count that final rest and you get the familiar four minutes. Here’s how common sessions add up with the standard 20/10 × 8 format, not counting the get-ready time.

Planning around a time limit

Short on time? Work backwards. A 10-minute window fits two classic Tabatas with a minute between them plus a quick countdown. Twenty minutes fits four, which is enough for a full-body session. Move the sliders until the total in the stat bar matches the time you actually have.

The method comes from a 1996 study led by Japanese researcher Izumi Tabata. One group of trained athletes cycled at a moderate, steady pace for an hour at a time. The other did seven to eight 20-second sprints on a cycle ergometer at about 170% of their VO2max, resting 10 seconds between each one.

It was one of the first studies to show both energy systems improving from a single type of training. Most gym Tabatas are a lighter version of that punishing effort, and that’s fine. Bodyweight and kettlebell Tabatas still make an efficient, demanding conditioning session, as long as you push hard in every work interval.

Not everyone should start with eight all-out rounds. Use these Tabata tiers to match the timer to your fitness, and move up a tier once the current one feels manageable for two or three sessions in a row.

Pick movements you can perform explosively and safely while tired. Pairing upper and lower body exercises lets one muscle group recover while the other works. Each workout below loads four Tabatas with a minute between them, and the timer names every exercise as you go.