How heart rate zone calculator works
Your heart rate zones are ranges of beats per minute (bpm) tied to exercise intensity. Training in the right zone targets a specific energy system: Zone 1-2 builds easy aerobic base and fat burning, Zone 3 improves cardio fitness, Zone 4 raises your anaerobic threshold, and Zone 5 develops VO2 max and sprint power. Enter your age (and resting heart rate for the Karvonen method) and the tool maps your personal max heart rate onto five zones.
Max heart rate (HRmax) is estimated from age. The classic Fox formula is 220 minus age. Tanaka (208 minus 0.7 x age) and Gellish (207 minus 0.7 x age) are more accurate, research-backed updates. If you know your measured max from a field test, choose Custom and enter it directly. The estimate is a population average, so your real max can vary by 10-12 bpm.
Two methods convert HRmax into zone ranges. Percent-of-max uses a straight percentage of HRmax (e.g. Zone 3 = 70-80% of HRmax). Karvonen uses heart rate reserve (HRmax minus resting HR) and adds resting HR back, which accounts for your resting fitness and is more accurate for trained individuals. Each zone is then reported as a low-high bpm range you can target during a workout. This is an estimate for education only, not medical advice.