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Heart Rate Zones Calculator

Calculate your maximum heart rate and training zones using the Karvonen formula. Fat burning, aerobic, cardio, and anaerobic zones.

Sources: Karvonen MJ et al. (1957) — Heart rate and exercise intensity · ACSM — Guidelines for Exercise Testing and Prescription

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How to Calculate Training Heart Rate Zones

Knowing your maximum heart rate and training zones allows you to exercise effectively, choosing the right intensity for your goal: burning fat, improving aerobic endurance, or boosting performance.

Maximum Heart Rate (HRmax)

HRmax is the maximum number of heartbeats per minute your heart can reach under exertion. The classic formula is:

HRmax = 220 - age

This formula provides an estimate with a margin of error of plus or minus 10-12 bpm. For a precise measurement, a maximal exercise stress test would be necessary.

Training Zones with Karvonen

The Karvonen formula calculates zones considering resting heart rate, making the calculation personalized:

Target HR = ((HRmax - resting HR) x % intensity) + resting HR

The five training zones:

  • Zone 1 (50-60%): Fat burning — brisk walking, warm-up, active recovery
  • Zone 2 (60-70%): Aerobic — easy running, moderate cycling, endurance base
  • Zone 3 (70-80%): Cardio — moderate running, aerobic threshold, cardiovascular improvement
  • Zone 4 (80-90%): Anaerobic — high-intensity intervals, anaerobic threshold
  • Zone 5 (90-100%): VO2max — sprints, maximal efforts (trained athletes only)

How to Choose the Right Zone

For weight loss, zones 2-3 are ideal: you burn many calories at a sustainable intensity. For improving endurance, zone 3 is the heart of aerobic training. For boosting performance, intervals in zone 4 stimulate superior cardiovascular adaptations.

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Frequently Asked Questions

How do you calculate maximum heart rate?▼
The most common formula is 220 minus age. For example, at age 30 the estimated max HR is 190 bpm. More accurate formulas include Tanaka (208 - 0.7 x age) and Gulati for women (206 - 0.88 x age). This calculator uses the classic formula for zones and the Karvonen formula to calculate personalized ranges that also consider resting heart rate.
What is the Karvonen formula?▼
The Karvonen formula calculates training heart rate by considering resting HR: Target HR = ((HRmax - resting HR) x % intensity) + resting HR. Unlike a simple percentage of HRmax, Karvonen personalizes zones based on your fitness level (resting HR is an indicator of cardiovascular fitness). An athlete with a resting HR of 50 bpm will have different zones than a sedentary person with a resting HR of 80 bpm.
What is the fat burning zone?▼
The fat burning zone corresponds to 50-60% of heart rate reserve (Karvonen). At this intensity, the body primarily uses fat as an energy source. However, it is a myth that training only in this zone is the best way to lose weight: higher intensity workouts burn more total calories and fat in absolute terms, even though the percentage of fat used is lower.
How do you measure resting heart rate?▼
Resting HR is measured in the morning right after waking, before getting out of bed, in a calm state. Count the beats at the wrist (radial artery) or neck (carotid) for 60 seconds, or for 15 seconds and multiply by 4. A normal value for adults is 60-100 bpm, but trained athletes may have values of 40-60 bpm.