Heart rate zone calculator
Training zones from age-predicted maximum heart rate, using the Tanaka equation.
Age-predicted maximum heart rate
180 bpm
- Method
- Heart rate reserve (Karvonen)
| Zone 1 — very light | 120–132 bpm |
|---|---|
| Zone 2 — light | 132–144 bpm |
| Zone 3 — moderate | 144–156 bpm |
| Zone 4 — hard | 156–168 bpm |
| Zone 5 — maximal | 168–180 bpm |
What this does not capture
- Age-predicted maximum heart rate is a population average with a standard deviation of roughly 10 beats per minute. Your actual maximum can sit well outside the estimate.
- The older 220-minus-age formula, still widely repeated, systematically underestimates maximum heart rate in older adults. Tanaka's equation was derived to correct it and is used here.
- Beta blockers and several other medications lower heart rate directly, which makes any age-predicted zone meaningless while taking them.
- Zone boundaries are conventions, not physiological thresholds. Nothing changes abruptly when a heart rate crosses one.
Why 220 minus age is wrong
The 220-minus-age formula has no single published derivation and was never validated as a measurement. Tanaka and colleagues pooled 351 studies and then tested the result prospectively in 514 healthy people, arriving at 208 minus 0.7 times age.
The practical difference grows with age. At 25 the two formulas nearly agree; at 65 the older one is out by roughly a dozen beats per minute, which is enough to put someone in the wrong zone.
What zones are for
Zones are a way of prescribing intensity without a laboratory. They are useful for structuring training and largely irrelevant to whether exercise is good for you — the guideline thresholds for health benefit are expressed in minutes of moderate or vigorous activity, not in zones.
If you supply a resting heart rate, this uses the Karvonen heart rate reserve method, which scales zones between resting and maximum rather than as a flat percentage of maximum.
Sources
- Age-predicted maximal heart rate revisited — Journal of the American College of Cardiology
- Physical Activity Guidelines for Americans, 2nd edition — US Department of Health and Human Services