Heart Rate Calculator

Tanaka (208 - 0.7 x age) is the default here because it comes from a 2001 meta-analysis of 351 studies covering roughly 19,000 people, and it corrects a known bias in 220-age: the older formula overestimates max heart rate in younger adults and underestimates it in older adults. At age 60 the two formulas differ by about 6 bpm. 220-age is still offered because most gym charts and training plans are still built around it, which is useful if you need to reconcile with one of those.

Heart Rate Reserve (HRR) is your estimated max heart rate minus your resting heart rate -- it's the usable range your heart actually works within. This calculator uses HRR in the Karvonen formula (Target = HRR x intensity% + resting HR), which personalizes your zones to your own fitness level. Karvonen zones come out higher than the plain percentage-of-max zones at the same nominal intensity, because they account for your resting rate -- the two methods aren't interchangeable, so it's worth picking one and sticking with it.

The American Heart Association's normal adult resting range is 60-100 bpm. Below 60 (bradycardia) is often normal in well-trained people but worth mentioning to a doctor without that training history, or if paired with dizziness or fatigue. Above 100 at rest (tachycardia) is frequently explained by caffeine, stress, dehydration, or recent activity, but if it persists while genuinely rested, or comes with palpitations or breathlessness, it's worth having assessed.

Age-based formulas are population averages with a standard deviation of roughly 10-12 bpm, meaning your real maximum could reasonably sit about 20 bpm either side of the estimate -- and every zone boundary calculated from it inherits that uncertainty. The only way to know your actual maximum is a supervised graded exercise test. In everyday training, the talk test is a useful cross-check: Zone 2 should let you hold a conversation in full sentences.

Yes. Beta blockers, calcium channel blockers, and other rate-limiting medications lower both resting and maximum heart rate, which invalidates the age-based estimate this calculator relies on. The same caution applies if you have a pacemaker, atrial fibrillation, or known heart disease -- train with medical guidance rather than these formulas in those cases.