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.
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.
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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.