Method
The calculator estimates maximum heart rate as 220 minus age. Heart-rate reserve uses resting heart rate plus intensity multiplied by max minus resting heart rate.
Example
For age 40, estimated max heart rate is 180 bpm. With resting heart rate of 60 and a 50% to 85% reserve range, the target zone is about 120 to 162 bpm.
Common mistakes
Do not ignore medication, symptoms, heat or illness. Heart-rate response can vary widely from formula estimates.
Limitations
This is not exercise clearance or medical advice. People with cardiovascular conditions, symptoms or medication effects should follow clinician guidance.
References
- CDC: measuring physical activity intensity, accessed 2026-05-17.
- WHO: physical activity, accessed 2026-05-17.
Last reviewed: 2026-05-17