Cardio calculator
Maximum heart rate calculator
Predict your maximum heart rate from age across four published equations — and see how far the textbook 220 − age sits from the better ones. Free, instant, no sign-up.
| Equation | Prediction | Typical spread |
|---|---|---|
| Fox (220 − age) | 180 bpm | ±11 bpm |
| Tanaka (2001) | 180 bpm | ±7 bpm |
| Gulati (2010, women) | 171 bpm | ±7 bpm |
| Nes (2013) | 185 bpm | ±10.8 bpm |
A predicted maximum is a starting point — the coach sets zones you can actually train to.
What is maximum heart rate?
Your maximum heart rate is the highest your heart can beat during all-out effort. It is not a fitness measure — a fit person and an unfit person of the same age often share the same maximum, and training barely moves it. What it does is set the top of the scale every heart rate zone is calculated from, which is why getting it roughly right matters and getting it exactly right rarely does.
How this calculator works
Four regressions of maximum heart rate on age. Fox, Naughton and Haskell (1971) gave the familiar 220 − age, which was a line drawn through pooled data rather than a fitted equation. Tanaka, Monahan and Seals (2001) re-fitted it across 18,712 people as 208 − 0.7 × age. Gulati et al. (2010) derived 206 − 0.88 × age on 5,437 women specifically. Nes et al. (2013) got 211 − 0.64 × age from the Norwegian HUNT3 cohort. We lead with Gulati for women and Tanaka for men.
Why the four disagree
220 − age is steeper than reality. It runs high for people in their twenties and low for people past fifty, and it overpredicts women at almost every age — which is the gap Gulati's equation was built to close. The equations happen to cross near age 40, so a 40-year-old man sees the same number from all of them and everyone else sees a spread. If you have ever wondered why your watch and your gym's chart disagree, this is usually why.
How accurate is it?
Not very, for an individual — and no equation on this page fixes that. The residual standard deviation is 7 to 11 bpm depending on the equation, so roughly a third of people sit outside the band shown above, and one in twenty is more than 20 bpm away from their prediction. Age genuinely explains only part of the variation. If your zones matter to you, replace the estimate with a measured maximum from a supervised ramp test or a hard hill-repeat session, and use the prediction only until then.