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Target Heart Rate Calculator
Aerobic, fat-burning and peak heart rate zones from age.
How it works
Maximum heart rate is estimated as 220 minus age, a rough average that has survived because it is simple and close enough for training guidance. If you enter a resting rate, the calculator switches to the Karvonen method, which builds zones from your heart-rate reserve, the gap between resting and maximum. That personalises the zones: a fit person with a low resting rate gets different targets from a beginner of the same age, which matches how training actually feels.
How to read the result
Light work suits warm-ups, recovery and long easy sessions; moderate work is the classic aerobic zone for building endurance; vigorous work is hard, sustainable only in intervals or shorter efforts. If you can talk easily, you are probably in the light-to-moderate range; if you can only manage short phrases, you are likely vigorous. Perceived effort is a useful cross-check whenever a watch reading looks suspicious.
One practical tip
Measure resting heart rate first thing in the morning, before coffee or your phone, over several days and average it. A single rushed measurement can be ten beats high, which shifts every Karvonen zone upward and makes easy sessions harder than intended.
If you take medication that affects heart rate, such as beta blockers, these zones will not apply in the usual way, so use perceived effort and your clinician's guidance instead of chasing a watch number.
Zone training works best when most weekly sessions stay easy and only a small share is vigorous, so do not spend every workout chasing the top zone in pursuit of a harder-looking session.