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Heart Rate Zone Calculator

Heart rate training zones help you optimize your workouts by targeting specific intensity levels. This calculator uses the Karvonen formula, which factors in both your maximum heart rate and resting heart rate to determine your Heart Rate Reserve (HRR) and produce more personalized zone ranges than simpler percentage-of-max methods.

Reviewed by GetHealthyCalculators Editorial Team · Updated April 14, 2026

Quick Answer

Your five heart rate training zones range from 50% to 100% of heart rate reserve, calculated with the Karvonen formula using your resting and max heart rate.

These results are estimates based on general formulas and are not a substitute for professional medical advice. Consult a healthcare provider before making health decisions.

Enter your age above to calculate your heart rate training zones.

How the Formula Works

  1. Determine your Maximum Heart Rate (MHR). The standard estimate is 220 minus your age, or you can enter a known value from a fitness test.

    MHR = 220 - age

  2. Calculate your Heart Rate Reserve (HRR) by subtracting your resting heart rate from your max heart rate.

    HRR = MHR - Resting Heart Rate

  3. For each zone, multiply your HRR by the zone intensity percentage, then add your resting heart rate back.

    Target HR = (HRR × %intensity) + Resting Heart Rate

  4. Repeat for both the lower and upper bound of each zone to get your BPM range.

    Zone range = [Target HR at low %, Target HR at high %]

How to Interpret Your Results

Each heart rate zone targets a different physiological adaptation. Training in lower zones builds aerobic endurance and promotes fat metabolism, while higher zones develop speed, power, and anaerobic capacity. A well-rounded training plan includes time in multiple zones based on your fitness goals.

Zone 1 — Recovery
50–60 — Light effort. Warm-ups, cool-downs, and active recovery sessions.
Zone 2 — Fat Burn
60–70 — Moderate effort. Long, easy runs and endurance base building.
Zone 3 — Aerobic
70–80 — Sustained effort. Tempo runs and cardiovascular improvement.
Zone 4 — Anaerobic
80–90 — Hard effort. Interval training and lactate threshold work.
Zone 5 — VO2 Max
90–100 — Maximum effort. Short sprints and peak performance training.

Limitations

  • The 220-minus-age formula for max heart rate is an estimate with a standard deviation of about 10–12 BPM. The Tanaka formula (208 − 0.7 × age) fits adult data better for some populations.
  • Resting heart rate varies with fitness level, stress, caffeine, dehydration, menstrual-cycle phase, and time of day. Measure first thing in the morning on three consecutive days and average for reliability.
  • Heart rate zones do not account for individual variations in fitness, genetics, body temperature, or cardiac drift during long sessions.
  • Medications (beta-blockers, calcium-channel blockers, stimulants) and arrhythmias (atrial fibrillation, heart block) can make heart rate an unreliable training signal.
  • Wrist-based optical heart-rate monitors can be inaccurate during high-intensity or cold-weather training; a chest strap is the more reliable tool.
  • This calculator is intended for generally healthy adults. Consult a healthcare provider before starting vigorous exercise, especially with cardiovascular disease, diabetes, or pregnancy.

Frequently Asked Questions

What is the Karvonen formula and why is it used?
The Karvonen formula calculates target heart rate by using your Heart Rate Reserve (the difference between your max and resting heart rate) rather than just a percentage of max heart rate. This produces more personalized zones because it accounts for your current fitness level through your resting heart rate.
How do I find my resting heart rate?
Measure your resting heart rate first thing in the morning before getting out of bed. Place two fingers on your wrist or neck, count the beats for 60 seconds (or 30 seconds and multiply by 2). Take measurements on three consecutive mornings and use the average for the most accurate result.
Is the 220-minus-age formula accurate for max heart rate?
The 220-minus-age formula provides a rough estimate but can be off by 10-12 BPM in either direction. For a more accurate value, consider a graded exercise test supervised by a fitness professional or healthcare provider. If you know your true max heart rate, enter it directly in the calculator.
Which heart rate zone is best for weight loss?
While Zone 2 (Fat Burn) uses a higher percentage of fat as fuel, total calorie burn increases with intensity. A mix of Zone 2 endurance sessions and Zone 3-4 interval training is generally most effective for weight loss, combined with a balanced diet. The best zone is one you can sustain consistently.
How often should I train in each zone?
A common approach is the 80/20 rule (polarized training, Seiler 2010): spend about 80% of your training time in Zones 1-2 (easy effort) and 20% in Zones 3-5 (moderate to hard effort). This balance builds a strong aerobic base while allowing adequate recovery.
Is the Tanaka formula more accurate than 220 − age?
Tanaka et al. (JACC 2001) analyzed 351 studies and found MHR = 208 − 0.7 × age had less systematic bias across adult ages than 220 − age, which tends to overestimate for people under 40 and underestimate for those over 60. Both have similar ±10–12 bpm standard deviation.
Why are my smartwatch zones different from this calculator?
Most smartwatches default to percentage-of-max-HR rather than Karvonen heart-rate-reserve zones, and some use lactate-threshold-based zones instead. The labels may look similar but the boundaries differ, which is why your Zone 2 on two devices can be 10–20 bpm apart.
Should I see a doctor before training in the higher zones?
If you are over 40, have cardiovascular risk factors (high blood pressure, high cholesterol, family history of early heart disease), have diabetes, or experience chest pain, dizziness, or unusual breathlessness with exertion, speak with your physician before training in Zone 4–5. The ACSM PAR-Q+ is a useful starting screen.
How do I know if my true max heart rate is very different from the formula?
Signs include: hitting "maximum" on easy efforts, or perceiving moderate effort at supposedly max-zone heart rates. A clinician-supervised graded exercise test is the definitive way to establish your true MHR and can reveal ECG abnormalities that exercise alone will not.

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