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Max
heart rate calculator
Three formulas rather than one, because they disagree — plus training zones that use your resting heart rate if you know it.
Why 220 minus age survives despite being wrong
It is memorable and it is roughly right in the middle of the age range, which is enough to keep any rule of thumb alive. It was never derived from a controlled study — it came from a loose fit through pooled data — and it systematically overestimates maximum heart rate in younger people and underestimates it in older ones.
Tanaka's equation, 208 minus 0.7 times age, was fitted to a large pooled dataset and tracks the age relationship better. Gulati's was derived in women specifically, and returns lower values than either of the others.
All three carry a standard deviation of around 10 beats. Two 35-year-olds can genuinely max at 175 and 195.
Heart rate reserve beats percentage of max
Zones taken as a straight percentage of maximum ignore where your heart starts.
Consider two 40-year-olds who both max around 180. One rests at 45, the other at 75. Seventy percent of max is 126 for both — but for the fit one that is barely above an easy jog, while for the other it is close to their resting-to-max midpoint. The Karvonen method fixes this by taking percentages of the gap between resting and maximum, so the same zone means the same relative effort for both.
That is why the resting heart rate field is worth filling in.
Most of your training belongs in zone 2
The common error in endurance training is spending most sessions in zone 3 — hard enough to accumulate fatigue, not hard enough to drive the adaptations that zone 4 and 5 work produces.
The pattern that works for most people is a large base of genuinely easy zone 2 work, where you could hold a conversation, plus a small amount of properly hard work. The middle ground feels productive and mostly buys tiredness.
Where heart rate misleads
It lags. At the start of an interval your effort is maximal while your heart rate is still climbing, so short intervals are better judged by pace or power.
It drifts. During a long steady session heart rate rises at constant effort as you dehydrate and heat up, which is normal and not a reason to slow down.
And it responds to everything else — heat, caffeine, illness, poor sleep, stress. A morning where your rate is 10 beats high for an easy pace is information about your recovery, not about your fitness.
Common questions
How do you calculate max heart rate?
The familiar rule is 220 minus your age, but it is the least accurate of the common formulas. Tanaka — 208 minus 0.7 times age — validates better across the adult age range, and Gulati (206 minus 0.88 times age) was derived specifically in women. All three are population estimates with a standard deviation of roughly 10 beats either side.
How accurate is 220 minus age?
Poor for individuals. It was never derived from a controlled study, and the true value for any given person can sit 20 beats above or below the prediction. Use it to set a starting point for zones, then correct from what you actually observe in hard sessions.
What are heart rate training zones?
Five bands describing effort. Zone 1 is recovery, zone 2 is the aerobic base where most endurance volume should live, zone 3 is tempo, zone 4 is threshold work, and zone 5 is short VO2 max intervals. This calculator uses the Karvonen method when you supply a resting heart rate, which makes the zones personal rather than generic.
What is the Karvonen method?
It takes percentages of your heart rate reserve — the gap between resting and maximum — rather than of maximum alone. A fit person with a resting rate of 45 gets meaningfully different zones from someone the same age resting at 75, which plain percentage-of-max cannot capture.
How do I measure my resting heart rate?
Take your pulse for a full minute immediately on waking, before getting out of bed, on three or four consecutive mornings and average them. A wearable that tracks overnight will do the same job. Rates measured after coffee or activity are not resting rates.
Should I train by heart rate or by feel?
Both, with feel as the tiebreaker. Heart rate lags at the start of intervals, drifts upward over long sessions at constant effort, and rises with heat, caffeine and poor sleep. If your monitor and your body disagree on a given day, your body is usually right.