Heart Rate Zone Calculator
Map training zones from an estimated maximum heart rate.
The 220-minus-age formula is a rough average
Every zone calculation starts from a maximum heart rate, and the familiar "220 minus age" estimate carries a standard deviation of roughly 10 to 12 beats per minute. That means a substantial share of people have a true maximum more than 20 beats away from the estimate — enough to shift every zone boundary far out of place. Newer formulas such as 208 − (0.7 × age) fit population data better, particularly for older adults, but none of them remove the individual variation.
The practical implication: if the zones feel systematically too easy or too hard, the formula is wrong for you, not your effort. A measured maximum from a supervised test, or a field test such as a hard 20-minute effort, gives far better boundaries.
Zones describe physiology, not colours on a watch
The useful distinction is between work below the first ventilatory threshold — conversational, sustainable for hours, where the aerobic base is built — and work above the second threshold, where lactate accumulates faster than it clears and duration collapses to minutes. Most of the named five-zone systems are approximations layered over those two real physiological boundaries. Zone 2 in particular has become popular precisely because it targets the sustainable aerobic range, but its boundary is individual and heart-rate estimates place it only approximately.
Heart rate is a laggy, noisy signal
Heart rate drifts upward over a long session at constant effort, rises with heat, dehydration, caffeine, illness, and poor sleep, and takes a minute or two to respond to a change in pace. For short intervals it is close to useless as a real-time guide because the effort ends before the heart rate arrives. Power meters for cycling and pace for running respond instantly and are better for prescribing short efforts; heart rate is most useful for capping long easy sessions and for tracking recovery over weeks.
How to use it
- Enter your age to generate an estimated maximum, or a measured maximum if you have one.
- Read the zone table as approximate ranges, not exact thresholds.
- Cross-check with perceived effort — zone 2 should allow full sentences.
- Adjust the boundaries if the perceived effort consistently disagrees with the numbers.
Common questions
How accurate is 220 minus age?
It is a population average with a standard deviation of roughly 10–12 beats per minute, so many individuals fall well outside it. Formulas such as 208 − (0.7 × age) fit the data better, but only a measured test gives your actual maximum.
Why do my zones feel wrong?
Almost always because the estimated maximum does not match yours. If every zone feels too easy or too hard by a consistent margin, shift the maximum until the perceived effort in each zone matches its description.
Is heart rate good for short intervals?
No. It lags a change in effort by a minute or more, so a 30-second interval is finished before the heart rate reflects it. Use pace or power for short efforts and heart rate for long steady ones.
Should I consult a doctor before hard training?
Yes, if you have any cardiovascular condition or symptoms, are on medication that affects heart rate such as beta blockers, or are returning to intense exercise after a long absence. Maximal testing in particular should be supervised.
Disclaimer: These estimates are general information, not medical advice, diagnosis, or treatment. Population formulas do not account for individual physiology, medication, or medical conditions. Consult a qualified clinician about your own health, and seek immediate care for any urgent symptom.