Tool
Heart rate zone calculator: five methods, and what your watch uses
At 40, five published formulas put your maximum heart rate between 180 and 185 bpm — and the measured spread between individuals is far wider than that, around 10 to 12 bpm either side. If you have ever seen a genuine maximum on a watch, use it; it beats every formula here.
How this works
Five estimates of one number, then the zones that follow from it.
220 − age. The famous one. Robergs and Landwehr went looking for the study behind it in 2002 and could not find one: it appears to have entered circulation as a rough fit to a scatter of data in the 1970s, and has been treated as fact since.
Tanaka: 208 − 0.7 × age. From a meta-analysis of 351 studies plus a prospective sample, and a better fit across ages. It is lower than 220 − age for people under 40 and higher for people over 40. At exactly 40 the two agree, which is a coincidence worth knowing about if you are testing formulas at that age.
Gulati: 206 − 0.88 × age. Derived from 5,437 asymptomatic women, and shown only when you select female, because that is the population it came from.
Karvonen: target = resting + percent × (max − resting). Not a maximum estimate but a zone method. It scales intensity across your heart-rate reserve rather than from zero, which matters most at the easy end.
Threshold percentages. If you know your lactate-threshold heart rate from a field test, zones anchored to it are more useful than zones anchored to a maximum you have never seen.
The number that matters more than the formula
Tanaka's own paper reports a standard deviation of roughly 7 bpm around the regression, and the commonly cited spread around 220 − age is 10 to 12. In practice that means two 42-year-olds can have genuine maxima of 168 and 194. Both are normal. Any formula gives them the same answer and is wrong for at least one of them.
That is the whole reason the tool prints the disagreement in the headline. A zone chart derived from an estimated maximum is a starting point that could easily be a zone off for you, and treating it as a diagnosis of your effort is how people end up convinced they cannot run easily.
If you have ever seen a maximum you trust — the highest figure from a hard race finish or a proper field test, recorded on a chest strap rather than a wrist sensor — enter it. It overrides every formula on the page, and it should.
What these zones cannot tell you
Whether a run was easy. Heart rate drifts upward over a long run at constant effort, rises in heat, rises when you are under-slept or ill, and takes several minutes to reflect a change in pace at all. A talk test disagreeing with your zones is not necessarily the talk test being wrong.
They also cannot tell you anything diagnostic. A high heart rate for your age during exercise is information about intensity and about the accuracy of your maximum, not a cardiac finding. Symptoms are what matter clinically, and they are a conversation with a doctor rather than with a calculator.
Questions runners actually ask
- Is 220 minus age accurate?
- It is a rough population average with no original research behind it — Robergs and Landwehr traced it in 2002 and found no study it was derived from. Tanaka fits real data better, but every formula carries a standard deviation of roughly 10 bpm, so any of them can be badly wrong for one person.
- Why does my watch say I was in zone 5 for an entire easy run?
- Usually one of three things: your maximum is set from a formula and is too low for you, the watch is using a wrist sensor that locked onto your cadence, or the run genuinely was not easy. The order to check them in is on the zones page.
- Should I use percent of max or Karvonen?
- Karvonen, if you know your resting heart rate — it accounts for the fact that your heart rate does not start at zero. The two methods can differ by 10 bpm or more in the easy zones, which is exactly the range where the difference decides whether a run is easy.
Sources
- Tanaka H, Monahan KD, Seals DR. Age-predicted maximal heart rate revisited. J Am Coll Cardiol 37(1):153-156, 2001 primary
- Gulati M et al. Heart rate response to exercise stress testing in asymptomatic women. Circulation 122(2):130-137, 2010 primary
- Robergs RA, Landwehr R. The surprising history of the HRmax = 220 − age equation. J Exerc Physiol Online 5(2):1-10, 2002 primary
- Karvonen MJ, Kentala E, Mustala O. The effects of training on heart rate. Ann Med Exp Biol Fenn 35(3):307-315, 1957 primary
- American Heart Association, target heart rates chart (reviewed 2024) reference
Changelog
- — First published.