Heart Rate Zone Calculator

❤️ Free Cardio Training Tool

Heart Rate Zone
Calculator

Discover your 5 personalised heart rate training zones — from fat-burning Zone 2 to max-effort Zone 5 — based on age, resting heart rate, and the Karvonen formula.

Science-Based Training Zones
Fat Burn Optimised
HIIT & Endurance Ready
30 yrs
Fitness level
Training goal
Maximum heart rate
0 bpm
Heart rate reserve (HRR): —
Formula: —
Training intensity spectrum (bpm)
💡 Personalised training insights:
—
🔵 Zone 2 (Fat Burn)
Use for long steady-state cardio: walking, easy cycling, light jogging. 45–90 min sessions, 3–5×/week builds the aerobic engine that powers all other zones.
🟠 Zone 4 (Threshold)
Tempo runs, cycling intervals, hard swimming. Hold for 20–40 minutes or use as 3–8 min intervals. Raises your lactate threshold — the single best predictor of endurance performance.
🔴 Zone 5 (Sprint/HIIT)
20–60 second all-out efforts. Use 1:3–1:5 work:rest ratios. Never daily — full neural and muscular recovery takes 48–72h. Max 2 Zone 5 sessions per week.
💤 Zone 1 (Recovery)
Light walking, easy swimming, gentle cycling the day after hard training. Active recovery in Zone 1 clears lactate and reduces soreness faster than complete rest.
⚠️ Disclaimer: This calculator provides general fitness estimates and is not medical advice. Consult a physician before starting a new exercise programme, especially if you have any cardiovascular conditions.

Heart Rate Zone Calculator: Optimize Your Cardio Training

Most people approach cardio with a simple goal: work hard, burn calories. But training without understanding your heart rate zones is like driving without a speedometer — you have no objective measure of effort, no way to target specific physiological adaptations, and no basis for progressive training. This free heart rate zone calculator gives you five personalised training zones based on your age and resting heart rate, using either the standard 220-minus-age formula or the more accurate Karvonen method (heart rate reserve), so you can train smarter — not just harder.

Quick answer: For a 30-year-old with a resting heart rate of 60 bpm — Max HR = 190 bpm; Zone 2 (fat burn) = 138–151 bpm using Karvonen; Zone 4 (threshold) = 164–177 bpm. Enter your details above for instant personalised zones.

How the Heart Rate Zone Calculator Formula Works

This calculator measures the range of heart rates you should target for a given training intensity, using your maximum heart rate (MHR) as the reference point. MHR is estimated from age using either the 220 minus age formula or the Tanaka formula, depending on which is more accurate for your age bracket. If you provide a resting heart rate, the calculator switches to the Karvonen method, which factors in your individual cardiovascular fitness rather than assuming everyone at the same age has the same training capacity. The units are always beats per minute (bpm). Read each zone’s range as the heart rate you should aim to stay within during that type of training, not an exact number to hit precisely. The formula assumes your entered age and resting heart rate are accurate; a resting heart rate measured after coffee, stress, or mid-day activity will produce zones that don’t reflect your true resting state.

1

Identify the inputs

You enter age, and optionally gender and resting heart rate (measured first thing in the morning, before getting out of bed).

2

Apply the formula

MHR = 220 minus age (or the Tanaka formula for ages over 40), with a small downward adjustment for female gender. If resting heart rate is provided, each zone boundary is calculated as (MHR minus resting HR) times the zone’s percentage, plus resting HR.

3

Perform the calculation

Using the example above: a 30-year-old with a resting HR of 60. MHR = 220 − 30 = 190. Heart rate reserve = 190 − 60 = 130. Zone 2 lower bound (60%) = 130 × 0.60 + 60 = 138.

4

Interpret the result

A Zone 2 range of roughly 138 to 151 bpm means staying within that heart rate during a training session targets fat oxidation and aerobic base building specifically, distinct from what a harder or easier effort would train.

3 Real-Life Examples

1. A young beginner relying on the calculator’s default settings

A 22-year-old male beginner enters his age and leaves the “Include resting heart rate” toggle unchecked, expecting the simple age-based method.

MHR = 220 − 22 = 198 bpm. With no resting heart rate entered, zones use the simple percentage-of-max method: Zone 2 (fat burn) comes out to 119 to 139 bpm.

Since he never checked the “Include resting heart rate” toggle, the calculator uses the straightforward age-based method throughout — no resting heart rate is required to get a usable set of training zones, though entering one (via the Karvonen method) typically produces a more personalised result.

2. An older, fit woman using the Tanaka and Karvonen methods together

A 52-year-old woman with a low resting heart rate of 48 bpm (a sign of good cardiovascular fitness) wants accurate zones for her training.

Since she’s over 40, MHR uses Tanaka: 208 − (0.7 × 52) = 171.6, then a −2 bpm gender adjustment gives 170 bpm. With Karvonen and her 48 bpm resting HR, Zone 4 (threshold) = 146 to 158 bpm.

Because her resting heart rate is well below average, the Karvonen method shifts her zones noticeably higher than a simple percentage-of-max calculation would, better reflecting her actual training capacity.

3. A HIIT athlete targeting Zones 4 and 5

A 35-year-old man with a resting heart rate of 65 bpm selects the HIIT training goal, which the calculator maps to Zones 4 and 5.

MHR = 220 − 35 = 185 bpm. With Karvonen, Zone 4 = 161 to 173 bpm, Zone 5 = 173 to 185 bpm.

The calculator highlights these two zones on the gauge and gradient bar as recommended for his goal, giving him a concrete heart rate ceiling to aim for during work intervals, with recovery intervals dropping back into Zone 1 to 2.

What Are Heart Rate Zones?

Heart rate zones are ranges of exercise intensity, expressed as a percentage of your maximum heart rate (MHR), that each trigger distinct physiological responses. Training in different zones produces different adaptations — Zone 2 training builds fat oxidation and aerobic efficiency; Zone 4–5 training builds speed, power, and anaerobic capacity. Most well-designed training programmes deliberately target multiple zones across the week to build a complete athletic profile.

The 5-zone model used by most coaches and sports scientists, and broadly consistent with the American Heart Association’s target heart rate chart, divides the intensity spectrum as follows:

Zone% of Max HRFeelPrimary fuelBest for
Zone 1 — Very Light50–60%Very easy, full conversationFatRecovery, warm-up
Zone 2 — Light60–70%Easy, short sentencesMostly fatFat burn, aerobic base
Zone 3 — Moderate70–80%Comfortably hard, phrases onlyFat + carbsAerobic fitness, tempo
Zone 4 — Hard80–90%Hard, single wordsMostly carbsThreshold, HIIT
Zone 5 — Maximum90–100%All-out, can’t speakCarbs (anaerobic)Speed, sprint intervals

Max Heart Rate Explained

Your maximum heart rate (MHR) is the highest number of times your heart can beat per minute during maximal exertion. It is primarily determined by age and genetics — unlike resting heart rate, it cannot be meaningfully improved through training. The two most commonly used formulas are:

220 − age formula (Fox, 1971): The most widely cited formula. Simple but carries a standard deviation of ±10–12 bpm — meaning for any given age, two-thirds of people will fall within ±12 bpm of the prediction, and one-third will be further away. Good for general use.

Tanaka formula (2001): 208 − (0.7 × age). More accurate for adults over 40. Derived from a meta-analysis of 351 studies. This calculator applies Tanaka for ages above 40.

Karvonen formula (1957): Uses heart rate reserve (HRR = Max HR − Resting HR) to calculate target zones. Accounts for individual fitness level via resting heart rate, producing more personalised and accurate zones. Enter your resting HR above to use this method.

The Fat Burning Zone Explained

Zone 2 (60–70% of max HR) is widely known as the “fat burning zone” — and for good reason. At this intensity, the body relies primarily on fat as its fuel source. Research consistently shows that fat oxidation peaks at approximately 65% of maximum heart rate and declines as intensity increases. At Zone 4–5 intensity, the body almost exclusively burns carbohydrates (glucose) because fat metabolism cannot supply energy quickly enough for high-intensity work.

However, the picture is more nuanced than simply “Zone 2 burns fat, higher zones don’t.” Higher-intensity training burns more total calories per minute, and the elevated post-exercise oxygen consumption (EPOC — the “afterburn effect”) following Zone 4–5 work means total calorie burn continues at an elevated rate for hours after exercise. For most people seeking fat loss, the most effective approach is a combination: Zone 2 for volume and fat oxidation capacity, plus one or two Zone 4 sessions per week for metabolic rate elevation and cardiovascular adaptation.

What Is Zone 2 Training?

Zone 2 training has attracted significant scientific attention, particularly following research by Dr. Iñigo San Millán at CU Sports Medicine. At Zone 2 intensity, the mitochondria (cellular energy factories) operate at their peak fat-oxidising capacity. Regular Zone 2 training increases mitochondrial density, improves the ability to clear lactate, and builds the aerobic base that underpins all higher-intensity performance.

Elite endurance athletes typically spend 75–80% of their training volume in Zone 2. This counterintuitive distribution — training mostly at conversational pace — builds the aerobic engine that allows them to sustain higher absolute speeds at lower relative intensities during competition. For recreational athletes, dedicating 2–3 sessions per week to Zone 2 cardio (45–90 minutes each) produces measurable improvements in aerobic capacity within 6–8 weeks.

HIIT vs Steady-State Cardio

High-intensity interval training (HIIT) involves alternating between Zone 4–5 intensity (work intervals) and Zone 1–2 (recovery intervals). Research supports HIIT as highly time-efficient — a 20-30 minute HIIT session can produce similar cardiovascular adaptations to 60 minutes of moderate steady-state cardio. However, this efficiency comes at a cost: HIIT demands 48–72 hours of recovery between sessions, limiting frequency to 2 sessions per week maximum for most people.

Steady-state Zone 2–3 cardio, by contrast, produces far less muscular damage and neural fatigue, allowing 4–6 sessions per week. The optimal training approach for most people combines both: 3–4 Zone 2 sessions per week for aerobic base development, plus 1–2 Zone 4 threshold sessions, and an optional Zone 5 session for speed and power. This “polarised” training model consistently outperforms training exclusively at moderate intensity in research settings.

How Athletes Use Heart Rate Zones

🏃

Runners

Elite marathon runners spend 80% of training in Zone 1–2, with focused tempo (Zone 3–4) sessions weekly. Heart rate zones allow objective pacing on varied terrain regardless of speed.

🚴

Cyclists

Power meters and heart rate monitors together enable precise zone training. Zone 2 “long slow distance” rides build fat oxidation; Zone 4 20-minute intervals raise functional threshold power.

🏊

Swimmers

Heart rate zones guide interval sets. Zone 3–4 200m repeats with 30-second rest build aerobic power; Zone 2 long sets build stroke efficiency and cardiovascular base.

🏋️

Gym athletes

Heart rate monitoring during circuits and CrossFit reveals actual training intensity. Many “moderate” gym sessions are actually Zone 3–4, accumulating more fatigue than planned.

Important Notes

What this calculator does and doesn’t cover

This tool applies the standard age-based and Karvonen formulas to the numbers you enter. A few things worth understanding before relying on the results:

  • Resting heart rate is only used when the toggle is checked. Leave “Include resting heart rate” unchecked and the calculator uses the plain age-based percentage method; check it and enter your own measured resting heart rate to switch to the more personalised Karvonen method.
  • MHR estimates carry real individual variation, commonly cited at about ±10 to 12 bpm around the age-based prediction, per the American Heart Association’s target heart rate guidance. About a third of people will have a true max HR further from the formula’s estimate than that.
  • Resting heart rate accuracy matters for Karvonen zones. Measure it first thing in the morning before getting up, not after coffee, stress, or activity, for a reliable reading. See Mayo Clinic’s walkthrough of the heart rate reserve method for a worked example matching this calculator’s approach.
  • The gender adjustment is a simplification. A flat 2 bpm reduction for female is a rough approximation, not a precisely validated correction across all ages and fitness levels.
  • Rounding. Figures are rounded to whole beats per minute for display.
  • Not medical advice. If you have a cardiovascular condition, are on heart rate affecting medication, or are new to structured exercise, consult a physician before training by heart rate zones.

Related Fitness Calculators

🔥 Calorie Burn Calculator
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🔥 TDEE Calculator
Your total daily energy expenditure with macro targets.
🏋️ One Rep Max Calculator
Estimate your 1RM for strength training programming.
💤 Sleep Cycle Calculator
Optimise recovery — sleep is when cardiac adaptations occur.

Frequently Asked Questions

What is my maximum heart rate?
Your maximum heart rate (MHR) is the highest number of times your heart can beat per minute during all-out exertion. The most common estimate is 220 minus your age, though more accurate formulas exist (this calculator uses the Tanaka formula — 208 − 0.7×age — for people over 40, which is validated in larger studies). MHR is primarily genetic and age-related — it decreases by approximately 1 bpm per year and cannot be significantly improved through training.
What is the fat burning heart rate zone?
The fat burning zone is typically Zone 2: 60–70% of maximum heart rate. At this intensity, fat is the predominant fuel source — your body has sufficient oxygen to metabolise fatty acids for energy. Fat oxidation peaks at approximately 65% of MHR for most people. However, “fat burning” doesn’t automatically mean the most effective zone for fat loss overall — higher intensities burn more total calories per minute. The optimal approach combines Zone 2 volume (for fat oxidation efficiency) with periodic Zone 4 intervals (for elevated metabolic rate).
What is Zone 2 training?
Zone 2 training is exercise performed at 60–70% of maximum heart rate — a conversational pace where you can speak in short sentences but breathing is noticeably elevated. It builds mitochondrial density, improves fat oxidation capacity, trains the cardiovascular system to efficiently deliver oxygen, and forms the aerobic base for all higher-intensity performance. Elite endurance athletes spend 75–80% of their training volume in Zone 2. Sessions should last 45–90 minutes for meaningful adaptation.
Is 220 minus age accurate?
It’s a reasonable estimate but carries significant individual variation — a standard deviation of ±10–12 bpm. This means about one-third of people will have an actual max HR more than 12 bpm different from the formula’s prediction. The formula is most accurate for sedentary individuals in their 20s–30s and least accurate for fit older adults. The Karvonen method (enabled by entering your resting heart rate in the calculator above) provides more personalised and accurate training zones by incorporating individual cardiovascular fitness.
What is the Karvonen formula?
The Karvonen formula (also called the heart rate reserve method) calculates target training heart rates using the reserve between resting and maximum heart rate: Target HR = (Max HR − Resting HR) × intensity % + Resting HR. This accounts for individual fitness — a well-trained person with a resting HR of 45 bpm will have different optimal zone boundaries than a sedentary person with a resting HR of 80 bpm, even at the same age. Karvonen zones are generally 5–15 bpm higher than simple percentage-of-max zones, which more accurately reflects true training intensity for fit individuals.
What is HIIT heart rate range?
Effective HIIT targets Zone 4–5: 80–100% of maximum heart rate during work intervals. Work intervals typically last 20 seconds to 4 minutes depending on the HIIT protocol (Tabata = 20s; Billat intervals = 4 min at VO2max pace). Recovery intervals drop to Zone 1–2 (50–65% MHR) to allow partial recovery before the next effort. True HIIT is significantly harder than most people’s “HIIT” workouts — if you can maintain conversation during the work intervals, you’re not working hard enough for the protocol to deliver HIIT’s documented benefits.
Can I train in Zone 5 every day?
No — Zone 5 training requires 48–72 hours of recovery between sessions. Maximum-intensity exercise creates significant muscle damage, depletes glycogen stores, elevates cortisol, and places high demand on the central nervous system. Training Zone 5 daily leads to overtraining syndrome within weeks — characterised by declining performance, elevated resting heart rate, poor sleep, mood disturbances, and increased injury risk. Most training programmes include just one Zone 5 session per week, complemented by Zone 1–3 work during recovery days.
Which heart rate zone burns the most fat?
Zone 2 burns the highest proportion of fat as a fuel source (60–80% of calories from fat). However, Zone 3–4 burns more total calories per minute. For total fat loss, the most effective approach depends on your available time and fitness level. If time is limited, Zone 4 HIIT burns more total calories in 30 minutes than 30 minutes of Zone 2. If you can train for 60–90 minutes, Zone 2 targets fat more directly and allows higher training frequency. Research supports combining both: 3–4 Zone 2 sessions plus 1–2 Zone 4 sessions per week for optimal fat loss alongside muscle preservation.
How long should I stay in each heart rate zone?
Optimal duration varies by zone: Zone 1 — 10–30 min (warm-up/cool-down). Zone 2 — 45–90 min per session (aerobic base building). Zone 3 — 20–40 min (tempo efforts). Zone 4 — 3–8 min intervals, total 20–30 min of work per session. Zone 5 — 20–60 seconds per interval, total 5–10 min of work. A general weekly volume guideline for recreational athletes: 70% Zone 1–2, 20% Zone 3, 10% Zone 4–5. This “80/20 training” distribution matches elite endurance athlete patterns and consistently outperforms middle-intensity exclusive training.
How do I measure my heart rate during exercise?
Options in order of accuracy: (1) Chest strap heart rate monitors (Polar, Garmin, Wahoo) — most accurate, particularly during high-intensity exercise; (2) Optical wrist-based monitors (Apple Watch, Garmin, Fitbit) — accurate for steady-state exercise, less reliable during intervals or weight training due to movement artefact; (3) Manual palpation — count carotid or radial pulse for 15 seconds and multiply by 4. For Zone-based training, a chest strap is strongly recommended as wrist-based monitors can lag 15–30 seconds and vary ±5–10 bpm, which meaningfully affects zone accuracy during intervals.

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