Heart Rate Zone Calculator
Estimate all five 50–100% heart-rate-reserve zones with consistent whole-BPM boundaries.
Your Heart Rate Zones Result
Result status:
Practical interpretation
Important: Estimate only—not medical advice.
How the Heart Rate Zone Calculator works
Formula: Predicted max = 208 − 0.7 × age; heart rate reserve = predicted max − resting HR; target = resting HR + intensity × reserve.
The accessible result table applies the Karvonen method for adults ages 18–81 at 50–60%, 60–70%, 70–80%, 80–90%, and 90–100% HRR, rounding each boundary to the nearest whole BPM.
Assumptions and limits: The calculator limits age to 18–81 to stay within the cited Tanaka study range. Maximum heart rate remains a population prediction, not an individual test. Medication, medical conditions, fitness, heat, fatigue, and device error can change observed response. Results are estimates for education and planning, not medical advice.
How to use your result
Use the result as a starting point, not a pass-or-fail score. Keep your inputs consistent, observe relevant trends over time, and adjust only when the trend—not one day—shows the estimate does not fit your needs.
Body measurements and equation-based targets always contain uncertainty. If your result conflicts with symptoms, a diagnosis, medication guidance, pregnancy needs, an eating-disorder recovery plan, or instructions from your care team, follow your qualified health professional.
Frequently Asked Questions
How is predicted maximum heart rate calculated?
For adults ages 18–81, the Tanaka equation predicts maximum heart rate as 208 minus 0.7 times age. It is a population estimate with meaningful individual uncertainty.
What is heart rate reserve?
Heart rate reserve is predicted maximum heart rate minus resting heart rate. The Karvonen method adds a percentage of that reserve back to resting heart rate.
What five zones are shown?
The table shows very light, light, moderate, hard, and maximum zones at 50–60%, 60–70%, 70–80%, 80–90%, and 90–100% of heart rate reserve.
How are BPM boundaries rounded?
Every lower and upper boundary is rounded to the nearest whole beat per minute with the same rounding method.
How should I measure resting heart rate?
Measure when awake, calm, and rested before activity. Use a reliable pulse count or device and consider several comparable readings.
Why must resting heart rate be below predicted maximum?
Karvonen zones require enough positive heart rate reserve to produce distinct whole-BPM bands. Values at or too close to the predicted maximum are rejected rather than producing collapsed or misleading zones.
Can medication or a health condition change my zones?
Yes. Heart-rate-altering medication, cardiovascular or autonomic conditions, heat, fatigue, and illness can materially change exercise response.
Are predicted heart-rate zones medical advice?
No. Use them as exercise-planning estimates. Follow clinician or cardiac-rehabilitation guidance when it differs from a calculator.
Scientific References
- Age-predicted maximal heart rate revisited Journal of the American College of Cardiology
- The effects of training on heart rate: a longitudinal study Annales Medicinae Experimentalis et Biologiae Fenniae
- ACSM Guidelines for Exercise Testing and Prescription American College of Sports Medicine