Heart Rate Zone Calculator
Five training zones, using heart rate reserve when you know your resting rate.
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Why 220 minus age is the wrong formula
The familiar 220 − age was never derived from research — it was an approximation noted in the 1970s that stuck. Its standard deviation is around 10-12 beats per minute, and it drifts badly with age, understating maximum heart rate for older adults. Tanaka's208 − 0.7 × age fits the data considerably better and is what this calculator uses. At 60 the two differ by six beats.
The bigger improvement is using heart rate reserve rather than a flat percentage of maximum. The Karvonen method takes the gap between your resting and maximum rates, applies the zone percentage to that, then adds the resting rate back. It accounts for fitness: a trained athlete with a resting rate of 45 gets meaningfully different zones from someone at 75, where a percentage of maximum would give them both the same numbers.
Zone 2 is where most endurance benefit is built, and it is almost universally trained too hard. It should feel genuinely easy — you should be able to hold a conversation in full sentences. The common pattern of training everything at a moderate-to-hard effort produces less adaptation than polarising between genuinely easy and genuinely hard. Note that any formula is an estimate; a laboratory test or a maximal field test gives your real figures.
Medical disclaimer. This calculator is for general information and education only. It is not medical advice, not a diagnosis, and not a substitute for professional care. Anyone with a cardiac condition, or taking beta blockers or other rate-limiting medication, needs zones set clinically — those drugs lower heart rate directly and make any age formula meaningless.Speak to a doctor or another qualified clinician about any health decision.Last reviewed .
Frequently asked questions
Why not use 220 minus age?
Because it was an approximation rather than a research finding, and it carries a standard deviation of 10-12 beats per minute. Tanaka's 208 − 0.7 × age fits observed data better, particularly over 40, where 220 − age increasingly understates the true maximum.
What is the Karvonen method?
A way of setting zones from heart rate reserve — the difference between your resting and maximum rates — rather than from a straight percentage of maximum. It produces higher and more individualised zones, because it accounts for how fit you already are.
How do I find my resting heart rate?
Measure first thing in the morning, before getting out of bed, over a full 60 seconds. Take it across several days and average them. Most fitness trackers record it automatically overnight, which is more reliable than a single manual count.
Which zone should I train in most?
For endurance, most of your volume should sit in Zone 2 — easy enough to hold a conversation in full sentences. The common mistake is training everything at moderate-to-hard effort, which produces less adaptation than polarising between easy and genuinely hard.
Do beta blockers affect these zones?
Substantially. Beta blockers and other rate-limiting medications lower heart rate directly, so any age-based formula becomes meaningless. Zones need to be set clinically, often using perceived exertion instead.