Maximum Heart Rate
Estimate your max heart rate from three well-known formulas, the anchor your training zones are built on.
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Learn the details
Max heart rate is estimated from age-based formulas: Fox (220 − age), Tanaka (208 − 0.7 × age), and Gulati (206 − 0.88 × age). Your true max can only be measured with a maximal exercise test.
Every treadmill and every watch will hand you a max heart rate based on your age and present it as a fact. It is an estimate, and a loose one. Here is where the number came from, how far off it can be for you, and what it does not tell you about your fitness.
Where 220 minus age came from
It was never a research finding. The line first appeared in a 1971 paper by Fox, Naughton and Haskell, who sketched it through data pooled from earlier studies of mixed quality. It was offered as a convenience, without a formal regression behind it and without an error estimate, and the authors did not claim it was precise. It spread anyway, because you can do it in your head. Fifty years on it is still printed on gym equipment, which tells you more about how memorable a formula is than how accurate it is.
How far off it can be for you
The real problem is not that the average is slightly wrong, it is how wide the spread around that average is. When max heart rate is measured directly, the standard deviation lands around 10 to 12 beats per minute at any given age. So two perfectly healthy 40 year olds can measure 170 and 195 and both be normal. Plenty of people sit 20 beats or more from what a formula predicts, and 20 beats is not a rounding error, it is an entirely different set of zones.
The better estimates, and a worked example
Tanaka, 208 minus 0.7 times age, came out of a 2001 meta-analysis pooling hundreds of studies and fits observed data better than the old rule, especially past 40. Gulati, 206 minus 0.88 times age, was derived from thousands of women and is the one this tool recommends for women, since the older equations tended to overshoot. Take a 55 year old: 220 minus age gives 165, Tanaka gives 170, Gulati gives 158. Twelve beats separate them before any individual variation is added on top.
A high max is not a fitness score
Max heart rate is largely genetic and it drifts down with age. It barely responds to training, and well-trained endurance athletes often measure a little lower than untrained people the same age, not higher. A max of 200 is not a badge and a max of 165 is not a flaw. What training actually improves is how much blood you move per beat and how long you can hold a hard effort, which shows up in your resting heart rate and your VO2 max, not in the ceiling.
Finding your real number
The only way to know your max is to go find it. A field test means a long warm up, then a progressive build over several minutes into an all-out finish, with a chest strap rather than a wrist sensor, and you keep the highest number it holds. Do it a few times and take the best reading. A maximal effort test is not for everyone though, and if you are new to hard training, older, on medication that affects heart rate, or have any known heart or blood pressure condition, talk to your doctor before you attempt one rather than after. Once you have a number you trust, build your training zones on it.
Sources: AHA target heart rate chart
If you train seriously, a field test like a graded treadmill test gives a more accurate max. Retest yearly or when your fitness level changes.