Five-Zone Heart Rate Training Calculator

About this calculator

The Karvonen method calculates training heart-rate zones using heart-rate reserve (HRR) — the gap between your maximum heart rate and your resting heart rate — rather than simply taking a percentage of max heart rate alone. The formula is target HR = ((max HR − resting HR) × intensity%) + resting HR, and applying it at five intensity bands (roughly 50-60%, 60-70%, 70-80%, 80-90% and 90-100% of HRR) produces the five classic training zones: recovery, aerobic base, tempo, threshold and VO2 max/anaerobic.

Because it factors in resting heart rate, the Karvonen method personalizes zones far better than a flat percentage-of-max approach — two athletes with the same max heart rate but very different fitness levels (and therefore different resting heart rates) get meaningfully different zone boundaries. Endurance coaches and athletes use these zones to structure training: easy days stay in zones 1-2 to build aerobic base without accumulating fatigue, while interval sessions deliberately target zones 4-5 to improve lactate threshold and VO2 max.

This calculator takes your age and resting heart rate and returns your five personal training zones using the Karvonen formula.