FREE TOOLS
40/20 interval timer
40 seconds of work, 20 seconds of rest, with a beep at every change, free in your browser
How to use it
- Pick 8, 10 or 12 rounds, or set your own.
- Open Warm-up, cool down and blocks to add a warm-up, or to repeat the rounds with a rest between them.
- Press Start: three short beeps warn you before each change.
Why 40/20?
Twice as much work as rest makes 40/20 one of the most common HIIT formats: long enough to do real work in each interval, with 20 seconds to breathe and get set for the next one. It suits circuits, bodyweight moves and kettlebell work. Read more about work and rest ratios.
| Rounds | Work | Rest | Total |
|---|---|---|---|
| 8 | 5:20 | 2:20 | 7:40 |
| 10 | 6:40 | 3:00 | 9:40 |
| 12 | 8:00 | 3:40 | 11:40 |
Workout ideas
- Bodyweight: squats, push-ups, mountain climbers and lunges, twice through.
- Kettlebell: swings, goblet squats, rows and presses.
- Circuit: one station per round, moving on in the 20 seconds of rest.
Questions
Is 40/20 good for beginners?
It’s hard for a first session. Start with 30 seconds of work and 30 of rest, and build up. See HIIT for beginners.
How many rounds of 40/20 should I do?
8 to 12 rounds is a common range, as on the HIIT timer page. Warm up for 5 minutes or more before you start.
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Cero is a timer, not a medical device. If you’re new to hard exercise, are pregnant or have a health condition, check with your doctor first, and stop if you feel unwell.