Heart Rate Zone Calculator
Estimate five training zones using the Tanaka maximum-heart-rate equation or optional Karvonen heart-rate reserve method.
Estimate five heart-rate zones
| Zone | Intensity | Estimated range |
|---|
Heart-rate zones are broad planning bands
The calculator uses the Tanaka population estimate, 208 − 0.7 × age. Karvonen mode applies percentages to heart-rate reserve after a resting heart rate is entered. The boundary percentages are configurable because zone systems differ.
Read the formula comparison and individual limitations.
Method reviewed 7 July 2026: Tanaka et al. and research on the wide agreement limits of age equations.
Heart Rate Zone FAQ
Which maximum-heart-rate formula does ToolBullet use?
The calculator uses the Tanaka population equation: 208 minus 0.7 times age. It is an estimate derived from group data, not an individual measurement.
What is the Karvonen method?
Karvonen applies the selected intensity percentages to heart-rate reserve—the difference between estimated maximum and resting heart rate—then adds resting heart rate back.
Why are my watch zones different?
Devices may use a different maximum-heart-rate formula, a measured value, proprietary zone boundaries or updated personal data. Check the method and percentages before comparing them.
How should I measure resting heart rate?
Use a representative calm reading under consistent conditions rather than an isolated value after activity, stress, caffeine or illness. Wearable and manual measurements can also differ.
Are these zones medical advice or exercise clearance?
No. They are broad planning estimates. Medical conditions, medications, symptoms and individual testing require appropriate clinical or professional assessment.