Heart Rate Zone Calculator

Every heart rate zone you have ever been shown started with a number nobody measured on you. Maximum heart rate is estimated from your age, and the two equations in common use agree exactly at forty and then part company in both directions, reaching fifteen beats a minute at ninety — so this page shows both, and the gap between them, rather than picking one and printing it as fact. The bands underneath are the percentage ranges the American College of Sports Medicine publishes for moderate and vigorous effort, applied to whichever equation you choose. Treat the whole thing as orientation: it tells you roughly where you are, not what your heart can do.

How it is calculated

Tanaka: HRmax = 208 − 0.7 × age · Traditional: HRmax = 220 − age · zone = HRmax × percent ÷ 100

The familiar 220 − age has less behind it than its ubiquity suggests. Tanaka, Monahan and Seals traced it to reviews by Fox and Haskell in the 1970s, where it was determined "arbitrarily" from ten studies whose oldest subject was under 65. Their own equation came from a meta-analysis of 351 studies and 18,712 subjects, cross-checked against 514 people measured in the laboratory, which gave the virtually identical 209 − 0.7 × age. The two lines cross at 40: below that the old equation runs high, above it the old equation runs low, by about ten beats a minute at seventy.

Source: Tanaka H, Monahan KD, Seals DR, "Age-Predicted Maximal Heart Rate Revisited", J Am Coll Cardiol 2001;37:153-6 — "In the meta-analysis, HRmax was strongly related to age (r = −0.90), using the equation of 208 − 0.7 × age." The meta-analysis covered 351 studies and 18,712 subjects; the laboratory arm of 514 subjects gave the "virtually identical" 209 − 0.7 × age

Questions people ask

Which of the two equations should I use?

Tanaka, unless something you already use was built on the other one. It rests on a far larger and better-documented sample, and it is the one that holds up past sixty, where the traditional equation is furthest out. If your watch or your gym chart uses 220 − age, keep to that rather than mixing the two, because the value of a zone is that it means the same thing week to week.

Why is 220 − age still everywhere if it is that shaky?

Because it is easy to remember and it was in print first. The paper that questioned it puts the origin in reviews by Fox and Haskell in the 1970s, notes the equation was determined "arbitrarily" from ten studies, and points out that the highest age included was under 65 — which is exactly the population where it now goes furthest wrong.

How far out can this be for me personally?

Further than the gap between the two equations. Across the whole age range the measured spread was 7 to 11 beats a minute either side of the line, and the authors note that for some older adults the traditional equation can be more than twenty beats out. An age-based estimate places you in a neighbourhood; only a measured maximum places you on a street.

Where do the percentage bands come from?

They are the American College of Sports Medicine ranges as quoted in a 2020 study in the International Journal of Exercise Science: moderate intensity is 64–76% of maximal heart rate and vigorous is 77–95%. This page shows those two and stops there rather than inventing the five-colour ladder your watch draws, because we have no published source for the extra boundaries.

Does the equation apply at any age?

The laboratory arm of the study covered ages 18 to 81, and everyone in it was free of overt coronary artery disease, did not smoke, and took no medication beyond hormone replacement. The paper names all three of those as things that move maximum heart rate independently of age, so outside that group the equation is an extrapolation.

Is this a training plan?

No, and it deliberately stops short of being one. It converts an age into an estimated maximum and applies two published percentage bands to it. What to do with that is between you and whoever knows your training and your health.

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