Heart rate zone calculator
Calculates target heart rates for ACSM intensity categories using either percentage of maximal heart rate or heart rate reserve (Karvonen). Enter a measured HRmax if you have one.
Inputs
Results
HRmax used
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| Category | RPE | %HRmax | Karvonen |
|---|
The formula
Predicted HRmax (Tanaka) = 208 − 0.7 × age
Predicted HRmax (traditional) = 220 − age
%HRmax target = HRmax × %
Karvonen target = (HRmax − HRrest) × % + HRrest
Predicted HRmax (traditional) = 220 − age
%HRmax target = HRmax × %
Karvonen target = (HRmax − HRrest) × % + HRrest
Limitations
- Age-predicted HRmax has an individual error of about ±10 bpm or more; a measured value is far better.
- Zones from formulas are not anchored to the individual’s lactate or ventilatory thresholds.
- Heat, dehydration, caffeine, stress, illness and long sessions (cardiac drift) raise heart rate at the same effort.
- Medications such as beta-blockers blunt heart rate — use RPE instead and follow clinical guidance.
Important
Stop exercise and seek medical advice if you experience chest pain, dizziness, palpitations or unusual breathlessness. People with heart disease or symptoms should get medical clearance before vigorous exercise.