Calculate training heart rate zones using Karvonen method for fat burn, cardio, and peak.
This calculator expresses Karvonen training intensity as bpm ranges rather than percentages alone. It works from resting heart rate and maximum heart rate, using their difference as heart-rate reserve; each zone percentage is applied to that reserve before resting rate is added back. It reports boundaries for fat-burn, cardio, and peak training. The common surprise is that a 70% Karvonen result is not 70% of maximum heart rate. Because the entries are personal health measurements, they remain in the browser and are not uploaded.
Karvonen begins with maximum heart rate minus resting heart rate. The result is heart-rate reserve, the adjustable span above rest. The calculator applies intensity to this span rather than to the full maximum. As a result, two people who share the same maximum rate but have different resting rates receive different bpm boundaries for otherwise identical zone percentages.
For each named band, its lower and upper percentages are evaluated with the same expression: resting bpm + (percentage x heart-rate reserve). Those two target values become the displayed bpm interval. Neighboring bands may meet at one value because the upper boundary of one can also be the lower boundary of the next; that shared endpoint is not a separate zone.
Karvonen percentages apply to heart-rate reserve, not directly to maximum heart rate. The calculator first subtracts resting rate from maximum rate, scales that smaller difference, and then restores the resting rate. A chart that multiplies maximum heart rate alone uses a different convention, so matching percentage labels can produce different bpm values.
No. The peak range is a mathematical band produced from the supplied heart-rate values and percentages; it is not a personalized finding that the entire band is safe. Maximum-rate estimates can miss an individual's actual response, and medicines or health conditions can alter exercise heart rate. Seek clinical guidance before using high-intensity targets when safety is uncertain.
The behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.
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