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HIIT Timer
Name
Rounds
Number of rounds
8
Intervals
Start on low intensity
Optional
Alerts
Other
Overrun
Notes
Color
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40/20 Interval Timer

The 40/20 HIIT timer: 40 seconds of hard work against 20 seconds of recovery, eight rounds through, eight minutes on the clock. The 2:1 ratio tips the session toward work — long enough that you can’t treat each interval as a sprint, short enough on rest that fatigue builds round over round.

This is the workhorse interval for conditioning circuits and bootcamp-style training, and it suits almost any movement: kettlebell swings, rowing, burpees, bike, battle ropes. Press start and the timer runs all eight rounds end to end. Want a warmup, more rounds, or a longer rest while you build up to it? Open the preset in the editor and set your own.

Good to Know

Frequently Asked Questions

How long is a 40/20 HIIT workout?
Eight minutes as loaded here: eight rounds of 40 seconds on, 20 seconds off. Add a warmup, a cooldown, or more rounds in the editor to lengthen it.
What does a 2:1 work-to-rest ratio train?
Working capacity under fatigue. Forty seconds is too long to sprint, so you settle into a strong, repeatable effort, and the short 20-second rest means each round starts a little less fresh than the last — the point is holding output as that pressure builds.
How many rounds of 40/20 should I do?
Eight is a solid default at eight minutes. Use the round count on the page to scale it — six for a quick finisher, ten or twelve when 40/20 has become comfortable.