How this calculator works
Maximum heart rate varies between people of the same age. The Tanaka age equation is an estimate, while the Karvonen method uses resting heart rate to tailor intensity bands.
Zone boundaries are useful for organising training, not biological walls. Your physiology does not switch systems exactly when a watch moves from Zone 2 to Zone 3.
Estimated HRmax = 208 − (0.7 × age). Target = resting HR + intensity × (HRmax − resting HR). This personalises zones beyond a simple percentage of maximum.
How to use the result
Easy aerobic work should usually feel conversational. Hard intervals should feel hard. When heart rate and perceived effort disagree, consider heat, dehydration, fatigue, caffeine, sensor error and medication.
A chest strap generally tracks rapid changes better than an optical wrist sensor. For medical exercise limits or cardiac rehabilitation, use the zones prescribed by your care team.
Get a more reliable result
Enter age and a true resting heart rate measured while calm—ideally after waking, before caffeine. The Karvonen method combines heart-rate reserve with an age-predicted maximum. Use zones as broad intensity guides and also monitor breathing, perceived exertion and symptoms.
Common errors that change the answer
- Treating an age formula as a measured personal maximum; individual variation can be substantial.
- Using noisy wrist-sensor spikes during intervals as if every reading were accurate.
- Ignoring medication, heat, dehydration, illness or symptoms that change heart-rate response.
What to do next
- Measure resting heart rate after waking, before caffeine, across several mornings.
- Use the talk test alongside the number.
- Update resting pulse as fitness, illness or medication changes it.
Guides that support this calculator
Frequently asked questions
Is 220 minus age wrong?
It is a rough older shortcut. The 208 − 0.7 × age model is another estimate and can still differ from your true maximum.
Which zone burns the most fat?
Lower intensities use a higher proportion of fat, but total energy, fitness and adherence matter more than a “fat-burning” label.
Why is my heart rate unusually high?
Heat, dehydration, illness, stress and stimulants can raise it. Stop and seek care for chest pain, fainting or concerning symptoms.