The Complete HIIT & Interval Timer Guide

Tabata, boxing rounds, EMOM, and custom intervals — explained, set up, and timed

Last updated: February 2026

High-Intensity Interval Training is defined by one thing: alternating periods of intense work and deliberate rest. The timer is not a convenience — it is the workout structure. The ratio of work to rest determines the training stimulus, the recovery between intervals determines how much quality output you can sustain, and the audio cues determine whether you actually move on time.

This guide covers the main HIIT interval formats used in fitness training — what each one is, how it works, and exactly how to set it up on iPhone using Box Timer. It also covers what separates a good interval timer app from a bad one, the mistakes athletes make most often with interval timing, and how the most popular HIIT timer apps compare.

The main HIIT interval formats

1. Tabata

Tabata is the most precisely defined HIIT protocol: 20 seconds of work followed by 10 seconds of rest, repeated for 8 rounds — exactly 4 minutes of total work. It originates from a 1996 study by Dr. Izumi Tabata at the National Institute of Fitness and Sports in Japan, which found that this specific 2:1 work-to-rest ratio produced greater improvements in both aerobic and anaerobic capacity than an hour of moderate-intensity cardio.

The 10-second rest interval is deliberately insufficient for full recovery. This is intentional — the accumulated oxygen debt across all 8 rounds is what drives the adaptation. Common Tabata movements include air squats, push-ups, burpees, thrusters, rowing, assault bike, and kettlebell swings. Any movement that can be cycled continuously for 20 seconds works.

Scoring: In structured Tabata protocols, the score is the lowest round count across all 8 rounds — penalising athletes who sprint the first four rounds and fade. In general fitness training, total reps across all rounds is a sufficient measure.

The beep at the work/rest transition is the defining feature of a good Tabata timer. At 10 seconds of rest there is no time to look at the screen — the audio cue is what tells you to start again.

2. Classic HIIT intervals

"HIIT" covers a wide range of work-to-rest ratios beyond Tabata. The protocol is the same — alternate work and rest, repeat for rounds — but the ratio shifts the training emphasis:

Shorter rest periods (2:1 and above) tax the anaerobic glycolytic system and build lactic acid tolerance. Longer rest periods (1:2 and below) allow near-full recovery between efforts and are better suited to maximal power output — sprints, jumps, or heavy barbell movements where quality degrades quickly under fatigue.

3. Boxing rounds

The standard boxing interval is 3 minutes of work followed by 1 minute of rest, repeated for 3 to 12 rounds. This format is used for shadow boxing, heavy bag work, pad work, and skipping rope in boxing and combat sports training. The 3:1 work-to-rest ratio produces a high aerobic load over multiple rounds while the 1-minute rest is long enough to lower heart rate meaningfully between efforts.

The boxing round format has crossed over into general fitness training widely. Many HIIT classes and home workouts use 3-minute rounds of mixed movements — burpees, jump rope, plyo push-ups, mountain climbers — followed by 1 minute of active recovery. The format works for any sustained-effort movement.

Amateur boxing typically uses 2-minute rounds. Elite amateur and professional boxing uses 3-minute rounds. Kickboxing and Muay Thai commonly use 3-minute rounds with 1-minute rest. All use the same timer structure — only the round duration changes.

Box Timer supports up to 99 rounds, making it suitable for long boxing sessions without reconfiguring mid-workout. The warning beeps in the final seconds of the rest interval replicate the corner man's cue to get off the stool.

4. EMOM-style HIIT

Every Minute On the Minute intervals apply HIIT principles in a self-regulating format: you work at the start of each minute and whatever time remains is your rest. If you complete 15 calories on the assault bike in 40 seconds, you get 20 seconds of rest. Move faster, recover more.

EMOM-style HIIT scales automatically by fitness level without changing the timer settings. A fitter athlete finishes faster and recovers more. A newer athlete finishes slower, works harder, and has less rest — which is the appropriate stimulus for their level. This makes EMOM intervals well suited to group training and partner workouts.

Common EMOM HIIT setups: 12 calories on the rower every minute for 10 rounds, 10 kettlebell swings every minute for 12 rounds, 15 wall balls every minute for 8 rounds, 5 strict pull-ups every minute for 10 rounds. The movement should be completable in 30–45 seconds to leave meaningful rest.

5. Custom intervals

Beyond the standard formats, HIIT training uses custom ratios for specific goals, programming styles, or athlete populations. Some examples:

• Beginner HIIT: 20s work / 40s rest for 6–8 rounds — lower total density, easier to sustain quality
• Sprint intervals: 10s work / 50s rest for 10 rounds — short maximal efforts with near-full recovery
• Strength-endurance: 50s work / 10s rest for 5 rounds — high time under tension, minimal rest
• Pyramid HIIT: start short and increase — but this requires reconfiguring between rounds, which Box Timer's saved workout history can assist with

Box Timer's interval mode accepts any work duration, rest duration, and round count. Any custom HIIT protocol that follows a fixed work/rest structure can be set up in seconds and saved for future sessions.

What to look for in a HIIT timer app

Most general timer apps — including the iPhone's built-in clock — can run a countdown or a stopwatch, but they cannot handle HIIT intervals. There is no interval mode, no work/rest separation, and no automatic round transitions. Here is what a dedicated HIIT timer app needs to deliver:

• Loud, distinct audio cues — During max-effort burpees or kettlebell swings you cannot check the screen. Warning beeps in the final 3 seconds of a rest interval are as important as the start-of-work beep. The timer needs to be audible over music and heavy breathing.
• Music compatibility — HIIT training without music is rare. The timer app should mix its beeps over your playlist using system audio — not pause or reroute it. Apps that use video-style audio channels cut the music every time a beep fires.
• Configurable work, rest, and rounds independently — A fixed Tabata-only app won't work for boxing rounds or custom 40/20 intervals. All three parameters need to be independently adjustable.
• No ads during workouts — A pop-up ad between rounds is not just annoying. It can add unexpected extra rest time and disrupt the interval structure. A freemium app with interstitial ads is not suitable for precision interval training.
• Screen stays awake — The display should remain on for the full duration of the workout. If it locks between intervals, unlocking it eats into rest time.
• Saved presets — If you run the same 30/30 circuit every Tuesday, you should be able to load it in one tap. Configuring from scratch before every session is wasted time and mental energy better spent warming up.

Common interval timer mistakes

• Not using a countdown lead-in — Starting an interval the moment you tap Start means you begin moving from a standing start. A 10-second countdown gives you time to get in position, grip the handle, or get your hands on the floor — which is especially important for Tabata where the first interval is at full intensity.
• Setting Tabata rest to zero — Some athletes new to Tabata think the rest period is optional and run 20/0 intervals. This is not Tabata — it is a sustained max-effort set that degrades into slow movement by round 3. The 10 seconds of rest is structural to the protocol.
• Using rest time for equipment transitions — In circuit HIIT with equipment changes (e.g. kettlebell to rowing machine), the transition can consume 10–15 seconds of programmed rest. Plan transitions into the rest interval, or add 10 seconds to the rest setting to account for them.
• Choosing an app that only does Tabata — Several popular timer apps are built exclusively for Tabata (20/10) or a fixed set of interval presets. Athletes who train across formats — Tabata one day, boxing rounds another, custom 40/20 intervals another — eventually outgrow these apps. Look for an app with fully configurable work, rest, and round settings.
• Cutting rest short "because it feels easy" — The adaptation from HIIT comes from repeating high-quality work intervals, not from grinding through fatigue. Shortening rest in the first half of a session leads to degraded output in the second half. The rest interval is part of the program.
• Not saving workouts — If you configure the same boxing round timer from scratch before every session, you are spending cognitive energy that should go into the warm-up. Save and name your frequent interval setups so you can reload them with one tap.

HIIT timer app comparison

The most commonly used HIIT and interval timer apps for iPhone, compared on the features that matter most for interval training:

Apps limited to Tabata presets cannot support boxing rounds, custom work/rest ratios, or EMOM-style intervals without workarounds.

Frequently asked questions

What is the best free HIIT timer app for iPhone?

Box Timer is the best free HIIT timer app for iPhone. It is completely free with no ads, no subscriptions, and no in-app purchases. It supports fully configurable work time, rest time, and round count — so it handles Tabata (20/10 × 8), boxing rounds (3:00/1:00), standard HIIT (40/20, 30/30), and EMOM intervals without switching apps or paying to unlock features. The interval timer plays loud beeps at work/rest transitions and mixes them over your music without pausing playback.

What is the best work-to-rest ratio for HIIT?

There is no single best ratio — it depends on the training goal and intensity of the movement. A 2:1 ratio (e.g. 40s/20s) is the most common general HIIT prescription and works well for bodyweight and moderate-load movements. A 1:2 ratio (e.g. 20s/40s) is better for maximal-effort power work where quality degrades quickly under fatigue. For beginners, a 1:1 ratio (30s/30s) provides enough recovery to maintain consistent output. Tabata's 2:1 ratio (20s/10s) is intentionally punishing and is most effective for athletes with a moderate-to-high fitness base.

Is Tabata better than regular HIIT?

Tabata is a specific type of HIIT, not a superior alternative. The original Tabata study compared a very specific protocol (8 rounds of 20s/10s at 170% VO₂max) to 60 minutes of steady-state cardio at 70% VO₂max. The results showed Tabata improved both aerobic and anaerobic capacity more. However, the study subjects were highly trained speed skaters working at 170% of their maximum oxygen uptake — a level of intensity most recreational athletes do not reach. General HIIT with longer intervals and more rest can be equally effective and more sustainable for most people.

How long should a HIIT workout be?

Effective HIIT sessions typically run 15–30 minutes of total work time, not counting warm-up and cool-down. A classic Tabata session is 4 minutes of work (8 rounds), though most athletes stack 3–5 Tabata rounds across different exercises for a 12–20 minute session. A boxing workout with 6 three-minute rounds and 1-minute rest is 24 minutes total (18 minutes of work). HIIT sessions longer than 30 minutes of active work typically indicate that the intensity is too low to qualify as true high-intensity training.

Can I use my iPhone as a HIIT interval timer?

Yes — with the right app. The iPhone's built-in Clock app has a countdown timer and a stopwatch but no interval mode. It cannot automatically alternate between work and rest, does not play round-transition beeps, and requires manual restarting after each interval. A dedicated interval timer app like Box Timer handles all of this automatically: set your work time, rest time, and rounds once, and the app runs the entire session with audio cues at every transition.

Related: Free HIIT Timer for iPhone  ·  Free Tabata Timer for iPhone  ·  Free Interval Timer for iPhone  ·  Free Boxing Round Timer for iPhone  ·  CrossFit Workout Timer Guide  ·  Best Workout Timer Apps for iPhone in 2026