⏲️ Interval Training Work:Rest Ratio Calculator

Enter your work interval duration and desired work:rest ratio to calculate how long your rest period should be.

Work Interval (seconds)

Work:Rest Ratio

Number of Intervals

Turning a ratio into seconds

The ratio is read as two numbers either side of the colon, and the rest is scaled from the work bout by their quotient:

rest  = work × (rest part / work part)
cycle = work + rest
total = cycle × number of intervals

Sixty seconds of work at 1:2 gives 120 seconds of rest, a 180-second cycle, and eight of those is 24m 0s. Flip to 3:1 and the same minute of work earns only 20 seconds back. The ratios above 1:1 are for threshold and tempo repeats, where the point is incomplete recovery; the ones below are for anything genuinely hard.

Choosing the ratio

Session	Typical ratio
Short sprints, 10-20 s all out	1:5 or longer
VO2max repeats, 2-5 min	1:1
Threshold or cruise intervals	3:1 to 5:1
Classic HIIT circuits	1:2

The dropdown stops at 1:3, so for a true sprint session put five times your work time into the work box, read the 1:1 rest, and use that as your recovery.

The total counts a rest after the final interval, so the real session ends about one rest period earlier - 22 minutes rather than 24 in the example above. Rest length is what decides which energy system you are training, so cutting it to save time turns a sprint session into a lactate session. General training information, not medical advice.

Frequently asked questions

What does a 1:2 work to rest ratio mean?

You rest twice as long as you worked. Thirty seconds hard buys sixty seconds easy, and the pair takes 90 seconds off the clock.

How long should I rest between 400m repeats?

Roughly as long as the repeat took, so a 90-second 400 gets a 90-second jog. That 1:1 keeps oxygen uptake high across the set, which is the point of the session; a full three-minute standing rest turns it into speed work.

What is the best work to rest ratio for HIIT?

1:1 or 1:2 for most people. Shorter rests than 1:1 mean the later intervals are run slower than the first, and once pace falls off you are no longer training the quality you set out to train.