Heart Rate Reserve Zone Calculator

This page applies user-selected lower and upper percentages to heart-rate reserve. Use either an entered maximum heart rate or the sex-neutral Tanaka age estimate. It does not attach a purpose, benefit, or intensity classification to the result.

Entries

Enter age from 15 to 100, resting heart rate from 40 to 120 bpm, and lower and upper percentages from 0% to 100%. The upper percentage must exceed the lower percentage. The starting values are age 30, 60 bpm, and 60–70%. If “Use custom max HR” is off, maximum heart rate is estimated as:

$HR_{\max}=208-0.7\times\text{age}$

If it is on, enter a maximum from 120 to 220 bpm. Maximum heart rate must exceed resting heart rate. The calculator performs arithmetic only; it does not determine whether a selected percentage is appropriate.

Heart-rate-reserve method

Heart-rate reserve is:

$HRR=HR_{\max}-HR_{\text{rest}}$

Each endpoint is then:

$HR_{\text{endpoint}}=HR_{\text{rest}}+HRR\times\text{selected percentage}$

The selected lower and upper percentages define the two endpoints. Endpoint values are rounded to whole bpm.

For age 30, the estimated maximum is $208-0.7(30)=187$ bpm. With a resting rate of 60 bpm, reserve is 127 bpm. The 60–70% band is:

$60+127(0.60)=136.2$ $60+127(0.70)=148.9$

The shown 60–70% range is therefore 136–149 bpm. If a maximum of 191 bpm is entered with the same resting rate, that band becomes 139–152 bpm.

Arithmetic workflow

1. Decide whether the maximum is age-estimated or entered, and record which.
2. Use a resting rate gathered under consistent conditions.
3. Record the selected lower and upper percentages with the result.
4. Do not infer an exercise purpose or benefit from the percentage-band arithmetic.
5. Recalculate when an input changes.

This range does not diagnose fitness or establish that an intensity is appropriate.

Sources

• Tanaka et al., Age-predicted maximal heart rate revisited — sex-neutral age equation.