Target Heart Rate (Clinical) Calculator

Target intensity directly scales the entire heart rate reserve in the Karvonen formula, so moving it from, say, 50% to 90% sweeps across nearly the whole working range between resting and maximum heart rate. Age and resting heart rate each only shift where that reserve's endpoints sit, a comparatively smaller effect on the final target for a typical adjustment, which is why intensity is the input clinicians and patients usually tune first when prescribing exercise.

It raises it, or at worst leaves it unchanged -- it never lowers it. A higher resting heart rate directly adds to the final target (it's added back in at the end of the formula) while also shrinking the heart rate reserve being multiplied by the intensity percentage; the direct addition outweighs that shrinkage at every intensity below 100%, so resting heart rate pushes the target upward across nearly the whole range. Exactly at 100% intensity the two effects cancel out and resting heart rate has no effect on the target at all -- it goes flat, not down, which is why the target equals the Fox-formula HRmax at maximum effort regardless of resting heart rate (see the next question).

No -- Karvonen's target is always at or above what the percentage-of-HRmax method would prescribe at the same intensity, never below. The two formulas differ by exactly resting HR x (1 - intensity/100), a term that's zero or positive everywhere in this calculator's declared ranges, so Karvonen's resting-heart-rate anchor pushes the target up relative to the flat percentage-of-HRmax method, most noticeably at low-to-moderate intensities for anyone with a nonzero resting heart rate (for example, 130 bpm from Karvonen versus 102 bpm from percentage-of-HRmax at this calculator's default age/resting-HR/60%- intensity inputs). The two methods agree exactly only at 100% intensity, where that gap term collapses to zero.

The Fox formula (220 - age) is the historically dominant, most widely recognized estimate and is what Karvonen's heart rate reserve calculation uses here, but it was derived from a smaller, less representative sample and tends to run high for older adults. The Tanaka formula (208 - 0.7 x age) comes from later, larger research and is generally regarded as more accurate across a broader age range, so showing both lets a clinician cross-check rather than relying on a single estimate.