Calculate heart rate reserve zones.
Heart-rate zones for Heart Rate Reserve use the Karvonen formula, adding a fraction of the heart-rate reserve to the resting rate to set a training target. Reserve-based targets adapt to fitness, so two people of the same age can train in very different zones.
Heart Rate Reserve
Target HR = resting + (max - resting) x intensity%
These are educational and reference calculations only. They are not a diagnosis, not a substitute for measurement or laboratory testing, and must not be used to start, stop, time or change any medication or treatment. Reference thresholds differ between national guidelines and do not account for your individual clinical context. Discuss any result that concerns you with a qualified healthcare professional, and seek urgent medical attention for acute symptoms rather than relying on a calculator.
Target HR = resting + (max - resting) x intensity% Heart-rate zones for Heart Rate Reserve use the Karvonen formula, adding a fraction of the heart-rate reserve to the resting rate to set a training target.
Reserve-based targets adapt to fitness, so two people of the same age can train in very different zones.
This calculator takes 3 inputs: Age, Resting heart rate, Target intensity. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.