What is the difference between Karvonen and percentage of max?

The percentage-of-max method takes simple fractions of your maximum heart rate. The Karvonen method uses your heart-rate reserve (max minus resting), which accounts for individual fitness and gives more personalised zones, especially for the lower zones.

Why use 208 minus 0.7 times age instead of 220 minus age?

The Tanaka formula (208 − 0.7 × age, 2001) fits large population data better than the older 220 − age rule, which tends to overestimate for young people and underestimate for older people.

Is my data sent anywhere?

No. Every calculation runs in your browser and nothing is uploaded.

Target Heart Rate Zone Calculator

Target heart rate zone calculator

Training in the right heart-rate zone matches your effort to your goal — recovery, fat-burning, aerobic base, or peak performance. This calculator gives you all five zones in bpm.

Maximum heart rate is estimated with the Tanaka formula: 208 − 0.7 × age, which fits population data better than the older 220 − age rule.

Two methods are available:

Karvonen (heart-rate reserve): zone = resting HR + intensity% × (max HR − resting HR). Personalised to your fitness.
% of max HR: zone = intensity% × max HR. Simpler, no resting HR needed.

Everything runs in your browser — nothing is uploaded.