Quick answer: at age 40 both common formulas give a maximum of 180 bpm (208 - 0.7 x 40 and 220 - 40). Zone 2 at 60 to 70% of that maximum is 108 to 126 bpm. With a resting heart rate of 60, the Karvonen method moves zone 2 up to 132 to 144 bpm.
How to use it
Choose where your maximum comes from. The Tanaka formula is the default; 220 minus age is offered because it is still widely used; the Tanaka paper calls it the commonly used equation. If you have seen a reliable maximum on a chest strap during an all-out effort, pick the third option and type it. A resting heart rate is optional: leave it blank for zones as a percentage of maximum, or fill it in for zones based on heart rate reserve.
The formulas
Tanaka, Monahan and Seals (2001) pooled 351 studies with 18,712 people and found maximum heart rate = 208 - 0.7 x age, with no difference by sex or activity level. The older 220 - age line is attributed to Fox and colleagues (1971). The two agree at age 40; younger, 220 - age is higher (200 against 194 at age 20), and older it is lower (160 against 166 at age 60).
Karvonen's method (1957) uses the reserve between rest and maximum: target = (max - rest) x % + rest. Because it starts from your resting pulse, a fit runner with a low resting rate gets zones that sit higher in absolute bpm than the plain percentage method.
Worked example
Age 35, Tanaka: 208 - 0.7 x 35 = 183.5 bpm. Zone 4 (80 to 90%) = 0.8 x 183.5 to 0.9 x 183.5 = 147 to 165 bpm. With a measured max of 190 and a resting rate of 50, the reserve is 140, so zone 2 = 50 + 0.6 x 140 to 50 + 0.7 x 140 = 134 to 148 bpm.
About the five zones
The 50-60, 60-70, 70-80, 80-90 and 90-100% bands are a common five-zone model, not a medical prescription and not the only scheme in use. Age formulas give a population average; your own maximum can sit well above or below it.
Not medical advice. If you take medication that affects heart rate (beta blockers, for example) or have a heart condition, ask your doctor for your training zones rather than using a formula.
Prefer to train by pace? The training pace calculator sets easy, threshold and interval paces from a race. For an aerobic fitness number, see the VO2 max calculator. A measured maximum from a graded test such as the Bruce protocol beats an age formula. For a simple fitness check at home, try the Harvard step test. Why the two age formulas differ, and by how much, is shown in the max heart rate formulas guide.
Sources: Tanaka, Monahan and Seals (2001), Age-predicted maximal heart rate revisited, J Am Coll Cardiol; Fox, Naughton and Haskell (1971), Physical activity and the prevention of coronary heart disease, Ann Clin Res; Karvonen, Kentala and Mustala (1957), The effects of training on heart rate, Ann Med Exp Biol Fenn; Maninthorn et al. (2025), Fox vs. Tanaka and percentage vs. Karvonen methods, Int J Exerc Sci. Rules checked . Found a problem? Tell us.
Questions
What is HRmax (maximum heart rate)?
HRmax is the highest heart rate you can reach in an all-out effort. A formula can only estimate it: the Tanaka formula, 208 - 0.7 x age, gives 187 at age 30 and 173 at age 50. Individual values vary widely around that estimate.
Is 220 minus age accurate?
It is simple and widely used, but the Tanaka study found 208 - 0.7 x age fits large groups better. The two give the same answer at 40 and drift apart for younger and older people.
What heart rate is zone 2?
In this five-zone model zone 2 is 60 to 70% of maximum, or of heart rate reserve if you use the Karvonen method. For a 180 bpm maximum that is 108 to 126 bpm without a resting rate.
Should I use the Karvonen method?
If you know your resting heart rate, it personalises the zones a little more, because it accounts for both ends of your range. Measure your resting rate on a few mornings and use a typical value.
What is heart rate reserve?
The gap between your maximum and resting heart rate. With a maximum of 180 and a resting rate of 60, the reserve is 120 beats, and 70% of it on top of the resting rate is 60 + 0.7 x 120 = 144 bpm. That is the Karvonen method.