Heart Rate Reserve Zone Calculator

The Heart Rate Reserve Zone Calculator applies user-selected lower and upper percentages to heart-rate reserve, using 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.

For training companions, pair the band arithmetic with the running pace calculator, the one rep max calculator, and the workout recovery time calculator.

Sources

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

• American Heart Association, Target Heart Rates Chart — Target heart-rate zone context: resting heart rate and percentage-of-maximum target zones in exercise guidance; supports the percentage-band arithmetic context, not an intensity classification.