The HIIT Intervals Chart: Work-to-Rest Ratios by Goal (With a Preset for Every Row)

HIIT intervals are decided by one number most people never choose on purpose: the work-to-rest ratio. Thirty seconds on and thirty off trains something different from forty on and twenty off - and both are different again from four minutes on, three off. This HIIT intervals chart lays out the twelve ratios worth using, what each one actually trains, how many rounds to run, and the heart-rate zone that proves you did it - with a preset on the free HIIT timer for every row so the programming decision is the only one left.

The chart

Effort = percentage of maximal output for the interval

Zones are percentage of max heart rate (Z4 ≈ 80-90%, Z5 ≈ 90-100%).

Every preset opens with sound cues and can be cast to a gym TV.

How to read the chart: the work-to-rest ratio decides the adaptation

The work-to-rest ratio is the programming variable, and the rule is simple:

• More rest relative to work = higher quality output = power and speed.
• Less rest = accumulating fatigue = conditioning and capacity.

1. 1:2 and 1:3 (rows 1, 12). Long rest means every interval is near your best - this is how sprinters and power athletes use HIIT intervals, and the safest ratio for beginners because output stays high and form holds.
2. 1:1 (rows 2, 3, 9). The balanced middle: sustainable across 8-10 rounds, trains speed endurance and aerobic power depending on interval length. The 30/30 HIIT is the best first HIIT workout anyone runs.
3. 2:1 (rows 4, 5, 10). The workhorse of class programming - 40/20 HIIT is the single most-used ratio in group fitness because it's hard, finishable, and coaches cleanly on a screen.
4. 3:1 and 4:1 (rows 6, 7). Rest is now too short to recover, so the adaptation is capacity under fatigue. Advanced ratios; run them for fewer rounds or as finishers.
5. Row 8 - 20/10 HIIT. Technically 2:1, but the maximal-effort prescription puts it in its own category - one dedicated block, not a class ratio. Where it sits against general HIIT and circuit formats is covered in Tabata vs HIIT vs circuit training.
6. Long intervals (rows 9-11). When work stretches past 90 seconds, you're training threshold and VO₂max, not speed. The 4×4 protocol is the most-researched HIIT format in endurance sport for a reason: four near-maximal 4-minute efforts move VO₂max more reliably than anything shorter.

FREE PRINTABLE COACHING TOOL

Get the Free HIIT Intervals Chart

Stop rebuilding work-to-rest ratios from memory.

Download the one-page Fit Viz HIIT Intervals Chart and keep proven timing structures within reach for class planning, personal training, and gym-floor coaching.

Inside the printable PDF:

1. Work and rest times at a glance
2. Typical round counts and total durations
3. Work-to-rest ratios and intensity targets
4. Best-use guidance for every interval structure
5. A quick-pick guide for choosing the right format
6. A QR code that opens the Fit Viz HIIT timer

How long should HIIT intervals be? (by goal)

1. Pick the work-to-rest ratio for the goal first then
2. Interval length follows from it:
   1. Fat loss / general conditioning: 30-60 second work intervals at 1:1 or 2:1 - rows 2, 4, 5. Total 10-16 minutes. Sustainable three times a week.
   2. Speed and power: 10-30 second work at 1:2 or 1:3 - rows 1, 12. Quality over volume; 8-10 rounds.
   3. VO₂max / endurance performance: 2-4 minute work at 1:1 to 4:3 - rows 10, 11. Once or twice a week, on machines or running.
   4. Class formats: 40/20 HIIT or 45/15 HIIT - rows 4, 6 - because they coach cleanly and finish on time.
   5. Beginners: row 2 (30/30) for 8 rounds. Add rounds before touching the rest.

Rounds, sets, and session length

The chart's rounds are single-block defaults.

Real sessions stack: 2 blocks × 8 rounds of 40/20 HIIT with a 60-second break is a 17-minute HIIT workout and a class staple (preset →).

Guidelines:

1. 10-25 minutes of total interval time
2. Short-interval ratios get more rounds (8-12), long-interval ratios fewer (4-6)
3. Breaks between blocks are 60-90 seconds - long enough to reload, too short to recover fully.

If you can do a third block at the same output, the first two weren't at the chart's effort level.

Progressing HIIT intervals (the order matters)

Move one dial per week, in this sequence:

1. Add rounds at the same ratio
2. Lengthen work at the same rest
3. Shorten rest
4. Move to a harder work-to-rest ratio.

Shortening rest first is the most common mistake - it collapses output and teaches pacing-down instead of pushing.

Six weeks on rows 2 → 4 → 6, adding rounds inside each, is a complete beginner-to-advanced progression.

Verifying intensity: The heart-rate check

Every row's effort column is a promise you can audit.

HIIT intervals that claim 90% effort should show heart rate reaching zone 4-5 by the third or fourth round and dipping only partially during rest - if rest drops you fully back to zone 2, the work wasn't hard enough or the rest is too long for the goal.

Live heart rate zones on a gym screen make this visible for a whole class at once; individually, any chest strap or watch does the job. Zone data is also how coaches catch the opposite error: athletes sitting in zone 5 on a "1:1 speed" day who need more rest, not less.

A sample week from the chart

Monday: Row 4 (40/20 × 8 × 2 blocks) after strength.

Wednesday: Row 3 (60/60 × 8) on a machine.

Friday: Row 12 (30/90 × 8) sprint repeats, or row 8 (one 20/10 block) for the experienced. Weekend: Easy aerobic work.

Three HIIT workouts across three work-to-rest ratios trains three systems - and never the same one twice in a row.

Coaching intervals for a room? Run any row on every screen with the Fit Viz workout display - the ratio, the round count, and the countdown beside the workout, with FitBeats shifting the music up on work and down on rest.

Common HIIT interval mistakes

1. Same work-to-rest ratio forever. 40/20 HIIT every session trains 40/20 HIIT - rotate rows.
2. Rest too short, too soon. See the progression order above.
3. Long intervals at sprint effort. Rows 9-11 are 85-90%, not maximal - pace them.
4. Guessing the switches. Ten- and twenty-second changes can't be counted at zone 5; use a clock that sounds them - every row above opens one on the free HIIT timer.