What is HIIT?
HIIT (High-Intensity Interval Training) alternates hard bursts of exercise with short rests. Because it loads both your heart and your muscles in a short session, it's a popular way for busy people to build an exercise habit. Common work-to-rest ratios are 2:1 (for example 40s + 20s) and 1:1 (30s + 30s).
How to use this HIIT timer
It's preset to 40 seconds of work and 20 seconds of rest for 8 sets. To run different moves in order — burpees, squats, mountain climbers — add one timer per exercise and give each a name and color, and it becomes a circuit timer that tells you what's next at a glance. Save and share any menu you build with its URL.
Example workout
Beginners can start with 30 seconds of work and 30 seconds of rest for 6 sets. As it gets easier, lengthen the work interval or add sets, and finish with a one-minute cool-down timer.