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About this tool
Compare Fox, Tanaka, Gulati, Nes and other age-predicted maximum heart rate equations side by side.
This comparator runs seven published age-prediction equations for maximum heart rate — Fox (220 − age), Astrand, Inbar, Tanaka (208 − 0.7 × age), Gellish, Gulati (206 − 0.88 × age, women) and Nes (211 − 0.64 × age) — on the same age and shows how far apart they land. Each result carries its prediction band of roughly ±10 bpm, the study it came from, and its difference from a measured maximum if you have one. The spread is the real lesson: at any given age these equations disagree by several beats, and the individual variation around each is larger still.
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Fox, Astrand, Inbar, Tanaka, Gellish, Gulati and Nes calculated together, each with its published source.
Every estimate is shown with its ±10 bpm prediction band rather than as a single confident figure.
Converts the suggested estimate into 50%, 60%, 70%, 80%, 90% and 100% of maximum heart rate.
For adults generally, Tanaka's 208 − 0.7 × age is the usual default because it came from a meta-analysis of 351 studies covering 18,712 people plus a prospective validation cohort. For women, Gulati's 206 − 0.88 × age was derived specifically from 5,437 women and predicts lower maxima. None is accurate for an individual — the standard deviation is about 10 bpm for all of them.
The Fox equation was never derived from a dedicated study; it was a convenient line drawn through data from several older sources. It tends to overestimate maximum heart rate in people under about 40 and underestimate it in older adults, and it carries a standard deviation of roughly 12 bpm.
At age 40 the estimates run from about 178 bpm (Inbar) to about 185 bpm (Nes) for a unisex calculation — a spread of around 7 bpm. The gap widens at the extremes of age, which is where the equations' differing slopes matter most.
Only a maximal exercise test measures it: a supervised graded treadmill or cycle protocol to volitional exhaustion, or a hard field test such as repeated uphill efforts with the peak recorded on a chest strap. Because maximal testing carries genuine cardiac risk, arrange it through a doctor or exercise physiologist, especially if you are over 40, sedentary, or have any cardiovascular symptoms or risk factors.
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