How the zones are worked out
Exercise intensity is easiest to track by heart rate, because it rises steadily with effort. The starting point is your maximum heart rate, which falls with age; most people estimate it from a formula rather than test it. Training zones are then bands of that maximum. If you enter a resting heart rate, the calculator switches to the Karvonen method, which applies the percentages to your heart-rate reserve — the beats between resting and maximum — so the zones reflect your fitness.
The formulas
Max HR (Fox / AHA) = 220 − age Max HR (Tanaka) = 208 − 0.7 × age Max HR (Gellish) = 207 − 0.7 × age Zone (% of max) = max HR × % Zone (Karvonen) = resting + % × (max HR − resting)
Worked example
At age 40, 220 − 40 = 180 bpm (Tanaka gives 208 − 28 = 180 too; the two agree at 40 and diverge with age — at 60, 160 vs. 166).
Zone 2 (60–70%) = 108–126 bpm. AHA moderate (50–70%) = 90–126 bpm; vigorous (70–85%) = 126–153 bpm.
With a resting pulse of 60, the reserve is 120 beats and Karvonen zone 2 becomes 60 + 0.6 × 120 = 132 to 60 + 0.7 × 120 = 144 bpm.
Limitations
- Age formulas have a standard error of about 10 bpm; your true maximum may be well above or below.
- Heat, dehydration, caffeine, stress and medications all shift heart rate.
- If you have heart disease or symptoms such as chest pain or dizziness on exertion, get medical clearance and a personal target range first.
Sources: American Heart Association, Know Your Target Heart Rates for Exercise, Losing Weight and Health; Centers for Disease Control and Prevention, How to Measure Physical Activity Intensity (talk test); Tanaka H, Monahan KD, Seals DR, "Age-predicted maximal heart rate revisited," J Am Coll Cardiol 2001;37:153–156; Gellish RL et al., Med Sci Sports Exerc 2007;39:822–829; Karvonen MJ et al., Ann Med Exp Biol Fenn 1957;35:307–315.
Frequently asked questions
What is my target heart rate for moderate exercise?
The American Heart Association defines moderate-intensity activity as about 50–70% of your maximum heart rate and vigorous activity as about 70–85%. For a 40-year-old with an estimated maximum of 180 bpm, that is 90–126 bpm for moderate and 126–153 bpm for vigorous exercise.
Which maximum heart rate formula should I use?
220 − age is the best known and the one the American Heart Association quotes, but it underestimates maximum heart rate in older adults. Tanaka et al. (2001), from a meta-analysis of 351 studies, found 208 − 0.7 × age fits better across ages. Both can be off by 10–12 bpm for an individual; a supervised maximal test is the only way to know.
What is the Karvonen method?
Instead of taking a percentage of maximum heart rate, Karvonen takes a percentage of your heart-rate reserve — maximum minus resting — and adds the resting rate back. It personalizes zones: a fit person with a low resting pulse gets higher targets at the same percentage. Measure your resting pulse in bed in the morning.
Do beta-blockers or other medicines affect this?
Yes. Beta-blockers and some other medications lower heart rate, so these zones will overstate your targets. Use perceived exertion (the talk test) instead and ask your doctor for a personal range.
What is the talk test?
A simple check from the CDC: during moderate activity you can talk but not sing; during vigorous activity you can say only a few words without pausing for breath. It works even when heart-rate numbers don't fit you.
This calculator is for general information and screening only and is not medical advice. Talk to a doctor or registered dietitian before making changes based on the result, especially if you are pregnant, under 18, or managing a health condition.