How to use this calculator
- Enter your age.
- Optionally enter your resting heart rate, measured in the morning before getting up (count beats for 60 seconds).
- Choose a maximum heart rate formula. Tanaka is generally more accurate than the classic 220 − age.
Formula
Maximum heart rate is estimated from age. With a resting heart rate, zones are calculated as a percentage of heart rate reserve (max − resting) added to resting HR.
Fox: HRmax = 220 − age
Tanaka: HRmax = 208 − 0.7 × age
Karvonen: target = (HRmax − HRrest) × intensity + HRrest
Example
- Age 35, resting HR 65, Tanaka formula: HRmax = 208 − 24.5 = 183.5 bpm.
- Reserve = 118.5; 70% intensity = 118.5 × 0.7 + 65 ≈ 148 bpm.
Frequently asked questions
How accurate are max heart rate formulas?
Individual max heart rate can differ from the formula by 10–20 beats per minute. A supervised exercise test gives the only true measurement.
What zone should I train in?
Most endurance training happens in zones 2–3 (moderate). Short intervals in zones 4–5 improve speed and capacity. Health guidelines recommend at least 150 minutes of moderate activity per week.
Does medication affect heart rate?
Yes. Beta blockers and some other medicines lower heart rate, which makes these zones unsuitable. Ask your doctor for personalized targets.