Heart Rate Zone Calculator
Your five training zones from age and resting heart rate, using the Karvonen method.
How it works
zone HR = resting HR + (max HR − resting HR) × intensity%
The Karvonen method anchors zones to your heart-rate reserve (max minus resting), which personalizes them better than plain percentages of max. Max HR here uses the common 220 − age estimate, which varies ±10–15 bpm between individuals.
Worked example
Age 35, resting 62: max ≈ 185, reserve 123. Zone 2 = 62 + 123×(0.60–0.70) ≈ 136–148 bpm.
Frequently asked questions
Is 220 − age accurate?
It’s a population average with wide individual spread. A field test (e.g. best 3-minute all-out effort) or lab test pins your true max better.
Why train mostly in Zone 2?
It builds aerobic capacity and fat metabolism with little fatigue cost, letting you accumulate volume that harder zones would not allow.
My watch shows different zones — why?
Devices use different schemes (percent of max vs reserve, 3–6 zone models). The bands here follow the five-zone Karvonen convention.
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This is a general educational estimate, not medical advice. Bodies differ — for decisions about diet, training, medication or health conditions, talk to a doctor or registered dietitian.