Estimate maximum heart rate, compare Tanaka and Fox equations, and calculate five training zones with a highlighted Zone 2 range.
Heart Rate Zones, Maximum Heart Rate, and Zone 2
Heart-rate zones divide an estimated or measured maximum into training-intensity bands. This calculator always shows the Tanaka and Fox maximum-heart-rate estimates, then builds zones with the selected percent-of-max method or the Karvonen heart-rate-reserve method.
Formula and Method
Tanaka maximum HR = 208 – 0.7 x age. Fox maximum HR = 220 – age. Percent-of-max target = maximum HR x intensity fraction. Karvonen target = resting HR + intensity fraction x (maximum HR – resting HR).
Five-zone model used in the calculator
| Reference | Range or value | Use or interpretation |
|---|---|---|
| Zone 1 | 50-60% | Very easy |
| Zone 2 | 60-70% | Easy aerobic |
| Zone 3 | 70-80% | Moderate |
| Zone 4 | 80-90% | Hard |
| Zone 5 | 90-100% | Very hard |
How to Use the Result
Choose one formula and use it consistently. Zone 2 is highlighted because it is a common steady-aerobic target, but definitions vary among coaches, devices, and laboratory systems. Compare a device’s labels with the percentages shown here before assuming they match.
Assumptions and Limitations
Maximum-heart-rate equations are estimates, and percentage boundaries are conventions rather than sharp physiological switches. Perceived exertion, talk-test response, pace or power, medication effects, and clinician guidance may be more useful than a formula for some people.
Sources
- Tanaka H, Monahan KD, Seals DR. Age-predicted maximal heart rate revisited, 2001.
- Fox SM, Naughton JP, Haskell WL. Physical activity and the prevention of coronary heart disease, 1971.