Heart Rate Zone Calculator

Your Heart Rate

Age

Resting HR (bpm)

Measure first thing in the morning before getting up

Max HR Method

Zone Calculation Method

Estimated Max HR

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Enter your age and resting HR

Max HR

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Resting HR

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HRR (Reserve)

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Aerobic Z2

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Threshold Z4

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Fat-Burn Zone

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MaxHR = 220 − Age Karvonen = (Max−Rest)×% + Rest HRR = Max − Rest

All 5 Training Zones

Zone	Name	% Intensity	BPM Range	Key Benefit	Duration
Calculate first

Zone Color Guide

Z1 Recovery — very light, gentle activity

Z2 Aerobic — comfortable conversational pace

Z3 Tempo — comfortably hard, limited talking

Z4 Threshold — hard effort, single-word answers

Z5 Max — all-out, very brief intervals

Zone Training Guide

How to find your true max HR: The most accurate way is a graded exercise test (GXT) under medical supervision. For self-testing: after a thorough warm-up, run hard uphill for 3 minutes, then sprint the last 30 seconds all-out. Note your highest HR reading. CAUTION: max HR testing is not appropriate for untrained individuals or those with heart conditions.

Karvonen vs. % Max HR: The Karvonen method (using heart rate reserve) is generally more individualized because it accounts for resting HR. Two people with the same max HR but different resting HRs will have different training zones under the Karvonen method.

The 80/20 rule: Research suggests most elite endurance athletes do approximately 80% of their training in Zone 1-2 (easy), and only 20% in Zone 4-5 (hard). Beginners often make the mistake of running too hard on easy days.

Zone 2 for fat burning: Zone 2 training (60-70% max HR) is optimal for fat oxidation, aerobic base building, and mitochondrial development. It's the foundation of endurance training. At very high intensities, carbohydrates become the dominant fuel.

Frequently Asked Questions

Which heart rate zone burns the most fat? +

Zone 2 (60-70% max HR) burns the highest percentage of calories from fat. However, higher intensity zones burn more total calories. For overall fat loss, total caloric deficit matters most, regardless of the fuel source during exercise.

Is the 220-minus-age formula accurate? +

The 220-minus-age formula is a rough population average with high variability (±10-20 bpm is common). Many individuals will be significantly above or below this estimate. For precision, a field test or laboratory test is needed. The Tanaka formula (208-0.7×age) is slightly more accurate for adults.

Why is Karvonen method better? +

The Karvonen method uses heart rate reserve (HRR = Max HR − Resting HR), which better reflects an individual's cardiovascular fitness. A highly fit person with a low resting HR (45 bpm) will have different absolute zone ranges than a sedentary person with RHR of 75 bpm, even with the same max HR.

Should I train at different heart rate zones? +

Yes. Polarized training (Z1/Z2 and Z4/Z5, avoiding Z3) has strong research support. Most recreational runners benefit from: 80% easy (Z1-Z2), 10% moderate (Z3), 10% hard (Z4-Z5). Varying zones develops different physiological adaptations.

What affects resting heart rate? +

Regular aerobic training lowers resting HR (elite athletes often 35-50 bpm). Factors increasing RHR: dehydration, illness, poor sleep, overtraining, high stress. RHR trending up over several days is an early sign of overtraining or illness — a useful monitoring metric.

How to Use This Calculator

Enter Age and Resting Heart Rate

Enter your age and resting heart rate. The calculator estimates max HR and computes Karvonen formula zones using heart rate reserve.

Optionally Enter Measured Max HR

Enter a field-tested max HR for greater accuracy than age-based estimates.

Review Your 5 Training Zones

Review Zone 1-5 ranges with training purpose and recommended weekly distribution for your goals.

Formula & Methodology

Max HR estimate = 207 - (0.7 x Age) [Gellish formula]

The Gellish formula reduces error vs the classic 220-age, especially for fit older athletes.

Target HR = ((Max HR - Resting HR) x Zone %) + Resting HR [Karvonen method]

Karvonen accounts for individual fitness by using Heart Rate Reserve (HRR) rather than raw max HR.

Key Terms

Heart Rate Reserve (HRR)

The difference between max HR and resting HR. Karvonen zones are calculated as percentages of HRR, then added back to resting HR, accounting for individual fitness level.

VO2max Zone

Zone 5 - maximal intensity training above lactate threshold. Used sparingly (5-10% of weekly training). Builds top-end speed and VO2max but requires significant recovery.

Lactate Threshold

The exercise intensity above which blood lactate accumulates faster than it clears. Training at and just below this threshold (Zone 3-4) is highly effective for race performance.

Zone 2 Training

Moderate aerobic zone (60-70% HRR). Often called 'conversational pace.' Research shows extensive Zone 2 work builds mitochondrial density and fat oxidation capacity - the aerobic base for all endurance sports.

Max Heart Rate

The highest heart rate your heart can achieve during maximal exertion. Decreases with age. Highly individual - age formulas have standard deviations of 10-12 bpm. Field testing is more accurate.

Karvonen Formula

Method for calculating target heart rate zones that uses heart rate reserve (max minus resting) rather than max HR alone, producing zones personalized to individual fitness level.

Real-World Examples

EXAMPLE 1

35-Year-Old, 60 bpm Resting HR

Inputs: Age: 35, Resting HR: 60 bpm, max estimated via Gellish

Calc: Max HR = 207 - (0.7 x 35) = 182.5 bpm | HRR = 182.5 - 60 = 122.5

Result: Z1: 60-85 | Z2: 85-110 | Z3: 110-134 | Z4: 134-158 | Z5: 158-182

EXAMPLE 2

50-Year-Old, Measured Max 172 bpm

Inputs: Age: 50, Resting HR: 55 bpm, measured max: 172 bpm

Calc: Gellish estimate = 207 - (0.7 x 50) = 172 bpm (matches measured) | HRR = 172 - 55 = 117

Result: Z2 target: 55 + (117 x 0.65) = 131 bpm | Z4 top: 55 + (117 x 0.90) = 160 bpm

Heart Rate Zones: The Polarized Training Approach for Endurance Gains

Heart rate zones transform subjective effort into objective, repeatable training intensity. The difference between Zone 2 and Zone 3 may feel subtle, but the physiological adaptations are distinct. Zone 2 (60-70% HRR) drives mitochondrial biogenesis and fat oxidation improvements that form the aerobic base for all endurance performance. Zone 4-5 work builds VO2max and lactate threshold. Blending intensities haphazardly - the classic 'moderate all the time' mistake - produces less adaptation than polarized training.

The Science of Zone 2 for Aerobic Base

Zone 2 training has received renewed attention from exercise physiologists and elite coaches. At this intensity, type I (slow-twitch) muscle fibers work aerobically with minimal lactate production. Sustained Zone 2 training over months increases mitochondrial density, improves fat oxidation at all intensities, and builds the capillary network that delivers oxygen to working muscles. This aerobic base supports faster recovery and allows higher volume of quality training.

Polarized Training: 80/20 Evidence

Research by Dr. Stephen Seiler and colleagues showed that elite endurance athletes across sports (running, cycling, rowing, cross-country skiing) predominantly train at approximately 80% easy (Zone 1-2) and 20% hard (Zone 4-5), with very little time in Zone 3 (moderate). This polarized distribution outperforms threshold-focused training (large amounts of Zone 3) in long-term development. For recreational athletes, this often means slowing down dramatically on easy days.

Measuring Your True Max Heart Rate

Age formulas (220-age or Gellish) have standard deviations of 10-12 bpm, meaning your actual max may be 20+ bpm different from the estimate. For accurate zones, test your true max: after a warm-up, run hard for 3-4 minutes at race effort, then sprint the final 30 seconds all-out. The highest number on your GPS watch during the test is your max. Perform this on a day when fully rested. Alternatively, your max from a very hard race effort is a reliable measurement.