Heart Rate Zone Calculator
Enter your age to calculate estimated maximum heart rate and the 5 training zones. Optionally provide your resting heart rate for more personalised zones using the Karvonen formula.
Reviewed by Richard Ross · Last updated April 2026
How Heart Rate Zone Calculator works
Maximum heart rate and the 220 − age formula
The most widely used estimate for maximum heart rate (MHR) is 220 minus age. For a 35-year-old, this gives an MHR of 185 bpm. This formula, while convenient, has a standard deviation of roughly 10–12 bpm — your actual maximum could be noticeably higher or lower. Other formulas such as 208 − 0.7 × age (Tanaka, 2001) are slightly more accurate for older adults.
The five training zones
Heart rate zones divide exercise intensity into bands, each producing different physiological adaptations. Zone 1 (50–60% MHR) is used for warm-up and recovery. Zone 2 (60–70%) builds aerobic base and fat-burning efficiency. Zone 3 (70–80%) improves aerobic capacity. Zone 4 (80–90%) raises lactate threshold — the point at which you can no longer sustain effort aerobically. Zone 5 (90–100%) develops maximal VO2 capacity.
The Karvonen method
The Karvonen formula provides more personalised zones by incorporating resting heart rate. It calculates heart rate reserve (HRR = max HR − resting HR) and applies zone percentages to that reserve: Zone target = (HRR × zone %) + resting HR. This adjusts for individual cardiovascular fitness — a person with a low resting heart rate (indicating higher fitness) will have wider absolute BPM zones than someone with the same maximum but higher resting rate.
Finding your resting heart rate
Measure resting heart rate first thing in the morning, before getting out of bed, over several days and take the average. Count your pulse for 60 seconds (or 30 seconds and double it). A typical resting heart rate is 60–100 bpm for adults; well-trained endurance athletes may have resting rates of 40–55 bpm. Lower resting heart rate generally indicates better cardiovascular fitness.
Frequently asked questions
What heart rate zone burns the most fat?
Zone 2 (60–70% of max HR) is often called the "fat-burning zone" because fat provides a higher proportion of fuel at lower intensities. However, higher-intensity zones burn more total calories per unit of time. For total fat loss, overall calorie expenditure matters more than the specific fuel mix. Zone 2 training is particularly valuable for building aerobic base.
How do I measure my maximum heart rate accurately?
The most accurate way is a graded exercise test (VO2 max test) supervised by a sports scientist or physiologist. A practical approach is a hard hill sprint or interval session where you push to maximum effort — your heart rate at the peak is close to your actual maximum. Note that MHR varies by sport and individual, and declines with age.
What is a dangerous heart rate during exercise?
For most healthy adults, training at high intensities (Zone 4–5) is safe and beneficial. You should be able to recover your heart rate to below 100 bpm within 2 minutes of stopping exercise. If you experience chest pain, severe breathlessness beyond what the effort should cause, dizziness, or irregular heartbeat, stop exercising and seek medical advice.
How accurate is the 220 − age formula?
The formula has a standard deviation of approximately 10–12 bpm, meaning two-thirds of people fall within 10–12 bpm of the prediction. It tends to underestimate maximum heart rate in older, fit adults and overestimate it in younger, sedentary people. For training purposes, the zones calculated from this formula are a useful starting point — monitor your perceived effort and adjust.
What is a normal resting heart rate?
A normal resting heart rate for adults is 60-100 beats per minute (bpm). Well-trained athletes may have resting rates of 40-60 bpm due to greater cardiac efficiency. A consistently low resting heart rate (bradycardia, below 60 bpm) is normal in fit people but may indicate a conduction problem in others. A consistently high resting rate (tachycardia, above 100 bpm) warrants medical attention if accompanied by symptoms such as dizziness, shortness of breath, or chest pain.
How do I measure my heart rate accurately?
The most accurate method is to count your pulse manually: press two fingers to your wrist (radial artery) or neck (carotid artery) and count beats for 60 seconds (or 30 seconds × 2). Measure resting heart rate in the morning before getting out of bed for the most consistent results. Optical heart rate monitors in smartwatches are convenient but less accurate during exercise with wrist movement. Chest strap monitors (Polar, Garmin HRM) are the most accurate wearable option for exercise.
How does fitness affect maximum heart rate?
Maximum heart rate (HRmax) is largely determined by age and genetics, not fitness. The common formula (220 − age) gives a rough estimate with a standard deviation of ±10-12 bpm. Fitness does not significantly raise HRmax, but it increases cardiac stroke volume (the amount of blood pumped per beat), allowing the heart to deliver more oxygen at any given heart rate. A fit person can sustain a higher percentage of their HRmax for longer, and their heart recovers faster after exertion.
What does heart rate variability (HRV) measure?
Heart rate variability (HRV) is the variation in the time interval between consecutive heartbeats. Higher HRV generally indicates better parasympathetic nervous system activity (the "rest and digest" response) and is associated with good cardiovascular fitness, recovery, and resilience to stress. Low HRV is associated with overtraining, poor sleep, high stress, and cardiovascular disease. Many fitness wearables (Garmin, Polar, WHOOP) now measure HRV as a recovery metric.
When should I be concerned about my heart rate during exercise?
During exercise, it is normal for heart rate to rise significantly. Concern arises if: your heart rate does not increase with exercise intensity (suggesting chronotropic incompetence); you experience heart rate above 85% of estimated HRmax accompanied by chest pain, severe breathlessness, or dizziness; your heart rate takes more than 5 minutes to fall below 100 bpm after moderate exercise stops; or you experience irregular heartbeat (palpitations or "skipped beats") during exertion. These symptoms warrant medical assessment.
What medications affect heart rate?
Several common medications significantly affect heart rate. Beta-blockers (metoprolol, atenolol, bisoprolol) lower resting heart rate and limit how high heart rate rises during exercise — standard heart rate training zones and HRmax formulas do not apply to people on beta-blockers. Thyroid medications may raise heart rate. Stimulants (including some ADHD medications and decongestants) raise resting heart rate. If you are on any cardiac or thyroid medication, consult your GP before using heart rate zones for exercise prescription.
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This calculator provides estimates for informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider.