heart rate training zones
A training zone is not a fixed number: it is a range calculated from an estimate of maximum heart rate, and that estimate changes depending on the formula used. This page shows where each number comes from and where the formulas disagree.
Fox estimates 170 bpm at age 50, 3 bpm below Tanaka for the same age; the gap carries proportionally into both training zones.
Tanaka is always equal to or higher than Fox from age 40 onward, because its per-year coefficient (0.7) is smaller than 1, which makes it gentler in older people.
Providing the real resting rate moves both the floor and ceiling of the two zones upward compared with the simple percentage-of-maximum method, because the calculation now starts from heart rate reserve, not from zero.
No. It is a simple population estimate and can be well off for a specific individual, real variation between people of the same age reaches tens of beats. Use the result as a starting point, not a hard limit.
There is no closed answer using a formula alone: Tanaka (2001) was published as an update to Fox (1971), and the gap between the two grows with age, from 0 bpm at 40 to 6 bpm at 60. An exact max heart rate value only comes from a direct physical test, and choosing between estimates should involve guidance from an exercise or health professional.
Karvonen calculates the training zone from heart rate reserve, the gap between maximum and resting rate, instead of applying the percentage directly to the maximum; that is why it needs a measured resting rate, a piece of data no age-based max heart rate formula supplies on its own.
Because the simple method applies the percentage directly to maximum heart rate (for example, 70% of 180 bpm), while Karvonen applies the percentage to heart rate reserve and then adds resting heart rate back in; the lower a person resting rate, the larger the reserve, and the bigger the gap between the two results.
It is the range between 50% and 70% of estimated maximum heart rate, the percentage definition used by this calculator; it is an intensity classification, not a training prescription, and any directed exercise plan should account for individual health history with professional support.
Medical notice: if you have a heart condition, symptoms, take medication that changes heart rate, or are starting to exercise, consult a health professional.
| Zone | Tanaka (208 − 0.7 × age) | Karvonen |
|---|---|---|
| Moderate | 92–129 | 125–148 |
| Vigorous | 129–156 | 148–166 |
Fox and Tanaka are different formulas for estimating max HR. The tool uses the selected method to calculate zones and shows the alternative alongside to avoid a false sense of absolute precision.
Fox: 220 − age. Tanaka: 208 − 0.7 × age. Moderate: 50–70%; vigorous: 70–85%. Karvonen uses heart rate reserve when resting HR is provided.
Age and resting heart rate stay in the browser and are not sent to analytics.