Heart-rate zones calculator
Training zones from age and resting heart rate.
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How it's calculated
Maximum heart rate is estimated as 220 minus age. The Karvonen method then works in heart-rate reserve, the gap between resting and maximum: each zone bound is the resting rate plus a percentage of that gap, which fits individual fitness better than a flat percentage of maximum. Switch to percent of maximum if you do not know your resting rate. The five zones run 50–60, 60–70, 70–80, 80–90 and 90–100 percent.
How accurate is 220 minus age?
It is an average with a spread of about ±10–12 beats, so a 40-year-old's true maximum could be anywhere from 168 to 192. The Tanaka formula, 208 − 0.7 × age, is slightly better for older adults. A measured maximum from a hard effort or a lab test beats both.
Which zone should I train in?
Most endurance plans put about 80% of training time in zones 1–2, easy enough to talk, and the rest in zones 4–5 as intervals. Zone 3 feels productive but is where many people spend too much time: too hard to recover from, too easy to build top-end fitness.
Why do Karvonen and percent-of-max give different numbers?
Percent of maximum ignores where your heart rate starts. For someone with a resting rate of 50 and a maximum of 180, 60% of maximum is 108 bpm, barely above walking; 60% of reserve is 128 bpm, a real easy run. Karvonen zones are higher and usually more useful for trained people.
Results are estimates for informational purposes only and are not financial, medical or legal advice.