What is a heart rate zone?

Heart rate zones are 5 ranges of exercise intensity defined as percentages of your maximum heart rate. Each zone targets different physiological adaptations: recovery, fat burning, aerobic capacity, lactate threshold, and maximum performance.

What are the 5 heart rate zones?

Zone 1 (50-60% MHR) Recovery — warm-up, cool-down, very easy. Zone 2 (60-70%) Fat Burn — easy conversational pace, aerobic base. Zone 3 (70-80%) Aerobic — moderate, sustainable for 60+ min. Zone 4 (80-90%) Threshold — hard, sustainable 30-60 min. Zone 5 (90-100%) Maximum — all-out, 30 sec to 5 min intervals.

What is the Karvonen formula?

Karvonen uses Heart Rate Reserve: Target HR = ((MaxHR − RestingHR) × intensity) + RestingHR. It's more accurate than simple % of MHR because it personalizes based on fitness (lower RHR = fitter). Our calculator uses Karvonen when you provide RHR.

How do I find my resting heart rate?

Measure first thing in the morning before getting out of bed, after waking naturally (no alarm). Take pulse at wrist or neck for 60 seconds, or use a smartwatch/fitness tracker overnight. Average 3-5 days for accuracy. Normal range: 60-100; athletes: 40-60.

Why train in Zone 2 if Zone 4 burns more calories?

Zone 2 builds aerobic base — the foundation for all other training. Pro athletes spend 80% of time in Zones 1-2 (polarized training). It develops capillaries, mitochondria, fat oxidation, and cardiovascular efficiency without the recovery burden of high intensity.

How long should I spend in each zone?

Polarized training: 80% Zones 1-2, 0-15% Zone 3, 15-20% Zones 4-5. Threshold training: 60% Zones 1-2, 30% Zone 3-4, 10% Zone 5. Pyramid training: 50% Zones 1-2, 30% Zone 3, 20% Zones 4-5. All work; pick based on goals and recovery capacity.

Can I calculate zones without a heart rate monitor?

Yes — use perceived exertion (RPE 1-10): Zone 1 = 3-4 ('easy talk'), Zone 2 = 5 ('easy talk in full sentences'), Zone 3 = 6 ('hard talk in short sentences'), Zone 4 = 7-8 ('breathless few words'), Zone 5 = 9-10 ('cannot speak'). Less precise but practical.

Are HR zones the same for running and cycling?

No — cycling MHR is typically 5-15 bpm lower than running for the same person due to different muscle recruitment. Calculate zones separately for each sport. Some athletes have a 'cycling MHR' and 'running MHR' that differ.

Heart Rate Zone Calculator

Heart rate training zones divide your cardiovascular range into 5 levels of intensity. Each zone targets different physiological adaptations: Zone 1 (Recovery) for warm-up and cool-down; Zone 2 (Fat Burn) for aerobic base building; Zone 3 (Aerobic) for cardiovascular improvement; Zone 4 (Threshold) for lactate threshold development; Zone 5 (Maximum) for VO2max and peak performance. Modern training research suggests spending 80% of time in Zones 1-2 (polarized training) — going easy when easy and hard when hard.

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calendar_today Updated: October 2025

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New

monitor_heartHR Zones (Karvonen)

Age

Resting HR

Max HR (optional override)

Auto-calculated from age if blank

analytics5 Training Zones

Max HR: 187 · HRR: 122

Input Values

Age

Resting Heart Rate

tips_and_updates Tips

• Spend 80% of training in Zone 1-2 (polarized training)
• Zone 2 is the 'maximum aerobic function' — fat burning + endurance base
• Zone 4 (threshold) develops lactate threshold for races
• Zone 5 only for short intervals (30s-4min)
• Beginners: stay in Zones 1-2 for 4-8 weeks before adding intensity
• Wear a HR monitor for accurate intensity tracking
• Recovery days should be Zone 1 only, not Zone 2

medical_information

Medical disclaimer. This calculator is for informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read here.

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Reviewed against authoritative guidelines

Last updated October 2025

Formulas, categories and healthy ranges align with Karvonen et al. 1957.

How to Use the HR Zone Calculator

Enter age

Used to estimate maximum heart rate.

Enter resting heart rate

Measure first thing in the morning.

Review 5 training zones

Each zone with HR range and purpose.

The Formula

The Karvonen method is more accurate than simple % of MHR because it uses heart rate reserve, which reflects individual fitness. A fit person with low RHR has a higher HR reserve and slightly different zones than an unfit person with the same age. Our calculator uses Karvonen automatically when RHR is provided; otherwise falls back to simple % of MHR.

Karvonen: Target HR = ((MHR − RHR) × intensity) + RHR

lightbulb Variables Explained

MHR Maximum heart rate (Tanaka: 208 − 0.7×age)
RHR Resting heart rate
HR Reserve MHR − RHR
Intensity % of HR reserve (0.50-1.00)

tips_and_updates Pro Tips

Spend 80% of training in Zone 1-2 (polarized training)

Zone 2 is the 'maximum aerobic function' — fat burning + endurance base

Zone 4 (threshold) develops lactate threshold for races

Zone 5 only for short intervals (30s-4min)

Beginners: stay in Zones 1-2 for 4-8 weeks before adding intensity

Wear a HR monitor for accurate intensity tracking

Recovery days should be Zone 1 only, not Zone 2

Heart rate training zones divide your exercise intensity into five distinct ranges based on percentage of maximum heart rate (MHR), each targeting different physiological adaptations. Zone 1 (50-60% MHR) builds basic endurance and aids recovery. Zone 2 (60-70% MHR) — the aerobic base zone — burns fat efficiently and is where most training volume should occur. Zone 3 (70-80% MHR) improves aerobic capacity and efficiency. Zone 4 (80-90% MHR) increases lactate threshold, the intensity you can sustain for 20-60 minutes. Zone 5 (90-100% MHR) develops VO2 max and anaerobic power for short, intense efforts. Training in the right zone is crucial — running too fast on easy days prevents recovery, while never pushing into higher zones limits performance improvement. Our heart rate zone calculator determines your personal zones from maximum heart rate (measured or estimated), resting heart rate, and age, using both the standard percentage method and the more accurate Karvonen formula that accounts for fitness level.

The five training zones explained

Zone 1 — Recovery (50-60% MHR): Very easy effort, conversational pace. Used for warm-ups, cool-downs, and recovery between hard sessions. Burns primarily fat but total calorie burn is low. Zone 2 — Aerobic Base (60-70% MHR): Comfortable effort, can speak in full sentences. This is the foundation of endurance training — marathon pace for elite runners. Builds mitochondrial density and capillary networks. Zone 3 — Tempo (70-80% MHR): Moderate effort, speaking becomes difficult. Often called the 'gray zone' because it is too hard for recovery but not hard enough for maximal adaptation. Limit time here unless specifically training tempo runs. Zone 4 — Threshold (80-90% MHR): Hard effort, only short phrases possible. Improves lactate clearance and sustainable race pace. Zone 5 — VO2 Max (90-100% MHR): Maximum effort, cannot speak. Short intervals of 30 seconds to 5 minutes with full recovery between.

Karvonen formula vs percentage of max HR

The simple percentage method (Zone = % × Max HR) ignores fitness level. The Karvonen formula uses heart rate reserve (HRR = Max HR - Resting HR) to account for fitness: Target HR = Resting HR + (HRR × target %). A fit runner with max HR 185 and resting HR 50 has HRR = 135. Zone 2 (60-70%): Karvonen gives 50 + 135×0.60 to 50 + 135×0.70 = 131-144 bpm. Simple method gives 185×0.60 to 185×0.70 = 111-130 bpm. The Karvonen result is 20+ bpm higher and more accurately reflects the actual effort level — 111 bpm would feel trivially easy for this athlete. The difference is most pronounced for fit individuals with low resting heart rates. For less fit individuals (resting HR 75-85), the two methods converge.

Practical zone training guidelines

The 80/20 rule is supported by extensive research on elite endurance athletes: approximately 80% of training volume should be in Zones 1-2 (easy), with 20% in Zones 3-5 (moderate to hard). Most recreational athletes make the opposite mistake — running too hard on easy days (Zone 3 instead of Zone 2) and not hard enough on hard days (Zone 3-4 instead of Zone 4-5). This all-Zone-3 approach produces mediocre results and higher injury rates. A well-structured weekly plan for a runner might include: 3-4 easy Zone 2 runs (base building), 1 tempo or threshold session (Zone 4, like 20-40 minutes at tempo pace), and 1 interval session (Zone 5, like 6×800m at 5K pace with recovery). Monitor zones using a heart rate monitor or chest strap — wrist-based optical sensors are accurate enough for zone training, typically within ±5 bpm.

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