Skip to content

Work-to-rest ratios for interval training: how to choose yours

5 min read
A woman doing sit-ups on a mat in a bright room
Photo by Jonathan Borba on Unsplash

The short answer

Choose the ratio from how hard the work interval is meant to be. For general conditioning at a hard but repeatable effort, 2:1 work to rest is a common starting point, such as 40 seconds on and 20 off for eight rounds. For efforts close to a sprint, rest two or three times as long as you work, or the later rounds stop being sprints. If you cannot hold the same output in the last round as the first, the rest is too short.

Open the interval timer

An interval session has three numbers: how long you work, how long you rest, and how many times. Most people pick them by copying a class or an app. The numbers make more sense once you see that the rest is what decides how hard the work can be.

The rest sets the intensity

You can only repeat an effort if you have recovered enough to produce it again. So the ratio follows from the kind of effort you want:

Effort in the work interval Typical ratio, work : rest Example Rounds
Hard but sustainable: you could say a few words 2:1 or 3:1 40 s on, 20 s off; 45 s on, 15 s off 8 to 12
Very hard: no talking 1:1 30 s on, 30 s off; 60 s on, 60 s off 6 to 10
Near sprint: all you have 1:2 to 1:3 or more 20 s on, 60 s off 4 to 8
Strength sets against the clock About 3:2 90 s on, 60 s off 5 to 6
EMOM Fixed minute Work, then rest for the remainder 10 to 20

These are starting points that coaches commonly use, not rules. The test of a ratio is simple: is the last round about as good as the first? If your output falls apart by round four, rest longer or work shorter. If round ten feels like round one, the work was too easy.

What short rests actually do

Cutting rest makes a session feel tougher, which is why it is popular. It also forces the work intensity down, because you start each round less recovered. Push it far enough and you are doing one long moderate effort with brief pauses. That is a fine session, but it is not the one you planned, and it does not train the top-end effort that intervals are for.

One well-known format does use a short rest deliberately: Tabata, 20 seconds on and 10 off. It works because the whole thing lasts four minutes and is meant to end in exhaustion.

EMOM: the clock does not wait

In an EMOM you start a fixed amount of work, such as ten kettlebell swings, at the top of every minute. Whatever is left of the minute is your rest. It is self-correcting: go faster and you rest more, slow down and the rest shrinks. If the work takes more than about 40 seconds of the minute, the set is too big to repeat for ten rounds.

Setting it up

The interval timer takes the three numbers directly: work seconds, rest seconds and rounds. There are presets for 40/20 × 8, 30/15 × 10, 45/15 × 12, 60/30 × 8 for circuit stations, a ten-round EMOM, and 90/60 × 6 for strength intervals.

Three things make it usable mid-set:

  • The whole screen changes colour, green for work and amber for rest, so you can tell the phase from across the room without reading a number. Open it on a TV or cast the tab, and go fullscreen.
  • A lead-in before round one. Every preset starts with a short prepare phase, so you can put the phone down and get into position.
  • A cue at every change. Switch to the loud bell in a noisy gym and keep your eyes on what you are doing.

Fullscreen carries no ads, and the interrupting ad formats stand down while a timer runs. The page asks the browser to keep the screen awake; on an iPhone that is less reliable than on a laptop, and plugging the phone in helps. A session you use often can be saved on that device, with no account.

A sensible progression

  1. Weeks 1 and 2: 30 s on, 30 s off, 8 rounds. Learn what a repeatable hard effort feels like.
  2. Weeks 3 and 4: 40 s on, 20 s off, 8 rounds. Same effort, less rest.
  3. After that: add rounds up to 12, or move to 45/15. Change one number at a time.

Warm up for five to ten minutes first, and stop a session when your form goes, not when the timer says so. If you have a heart condition or are returning from injury, ask a doctor before doing hard intervals.

  • Fitness
  • Timers

Questions people ask

What is a good work-to-rest ratio for HIIT?

For general conditioning, 2:1 is a common starting point: 40 seconds of work to 20 of rest. For harder efforts nearer a sprint, 1:2 or 1:3 lets you repeat the intensity. The right ratio depends on how hard the work interval is meant to be.

What does 40/20 mean in a workout?

40 seconds of work followed by 20 seconds of rest, repeated for a set number of rounds. Eight rounds takes eight minutes. It is a 2:1 ratio and suits bodyweight and conditioning circuits.

What is an EMOM?

Every Minute On the Minute. You start a fixed set of work at the top of each minute and rest for whatever remains of it. Finishing faster earns more rest, and the clock does not wait if you are slow.

How many rounds of intervals should I do?

Enough that the last round matches the first. For most people that is 6 to 12 rounds of a 2:1 format, or 4 to 8 all-out sprints with long rests. When output drops sharply, the useful part of the session is over.

Is a shorter rest always a harder workout?

It feels harder, but it lowers how hard you can work. Cut the rest far enough and intervals turn into one continuous moderate effort, which is a different session with a different purpose.

Keep reading