HR Zone Pro

Calculation Method

Max HR

Resting HR

Karvonen applies percentages to Heart Rate Reserve (Max - Resting), then adds resting heart rate back. It is a different convention from percentage of Max HR.

Zone	Range
Zone 1: Recovery	125 - 138 bpm
Zone 2: Endurance	139 - 151 bpm
Zone 3: Aerobic	152 - 164 bpm
Zone 4: Threshold	165 - 177 bpm
Zone 5: VO2 Max	178 - 190 bpm

About Advanced HR Zone Calculator

Compare heart-rate zones from percentage of entered maximum heart rate, Karvonen heart-rate reserve, or a running-specific LTHR model. The methods use different anchors and should not be treated as interchangeable measurements.

Choose a heart-rate zone method before interpreting the numbers

Maximum-heart-rate percentage, Karvonen heart-rate reserve, and lactate-threshold heart rate use different anchors. This calculator shows each model transparently; it does not claim that the resulting zone numbers are equivalent.

Use an entered maximum heart rate

The Max HR method applies fixed percentages to the maximum value you enter. This calculator does not estimate maximum heart rate from age. An observed peak, an age-predicted value, and a laboratory maximum can differ, so record which source you used when comparing zones later.

Zones 1–5 span 50–100% of the entered maximum.
Changing the anchor changes every boundary.
Medication and measurement error can change the relationship between heart rate and effort.

Karvonen adds resting heart rate

The heart-rate-reserve calculation subtracts resting heart rate from maximum heart rate, applies the selected percentage to that reserve, and then adds resting heart rate back. Enter resting and maximum values measured under conditions you can repeat.

Heart-rate reserve = maximum heart rate − resting heart rate.
The same maximum with a different resting value produces different zones.
A resting value must be positive and lower than the entered maximum.

LTHR uses a running-specific seven-zone table

The LTHR option follows Joe Friel's published running percentages around an entered threshold heart rate. It is a different seven-zone convention, not a more precise version of the five-zone Max HR or Karvonen tables.

Retest with the same protocol when fitness or conditions change. Do not compare zone numbers from different methods without keeping the method and anchor beside the result.

Why do Karvonen and maximum-HR zones disagree?

Karvonen applies percentages to the reserve between resting and maximum heart rate, then adds resting heart rate back. Percentage-of-maximum uses only the maximum, so the arithmetic and boundaries are different.

Does this calculator estimate my maximum heart rate from age?

No. It uses the maximum heart rate you enter. Age equations are population estimates and are not silently applied here.

Are LTHR zones the same for running and cycling?

Not necessarily. The displayed LTHR table is the published running-specific convention. Threshold heart rate and zone conventions can differ by sport, test, and platform.