How to use the HIIT interval timer
- Set the work and rest times, the number of rounds and, optionally, several sets with a longer break between them. Or tap a ready-made workout such as Tabata.
- Press Start (or the space bar). A short countdown gives you time to get into position.
- Follow the colours: red for work, green for rest. Three beeps count down the end of every interval, and a higher beep starts the next work period.
- Pause, skip or reset at any time. The screen is kept awake on supported devices.
What is HIIT?
High-intensity interval training alternates short bursts of hard effort with recovery. Common formats include Tabata (20 seconds all-out, 10 seconds rest, 8 rounds: four minutes in total, from a 1996 study by Izumi Tabata on Olympic speed skaters), 40/20 circuits that suit bodyweight exercises such as burpees, squats and mountain climbers, and EMOM (every minute on the minute), where you start a set of reps at the top of each minute and rest for whatever time remains.
Studies show that HIIT can improve aerobic fitness and insulin sensitivity in less time than steady cardio. It is demanding, so warm up for five to ten minutes, start with fewer rounds, and leave at least a day between hard sessions. Beginners can use longer rests, such as 30/30. If you have a heart condition, high blood pressure or joint problems, check with a doctor first; this timer is a training tool, not medical advice.
The timer runs entirely in your browser and works offline once loaded. Keep the tab visible for the most accurate timing.
Does the timer work with the screen off?
Browsers slow down background tabs, so keep the page open. Wake Lock keeps the screen on in Chrome, Edge and Safari 16.4+.
How long should a HIIT workout be?
The intervals themselves are often 10–25 minutes. Add a warm-up and cool-down.
Can I use it for circuit training?
Yes. Set the work time per station, the rest as transition time, and the rounds to the number of stations.