By Zencalcy Editorial TeamLast reviewed About us
Heart rate reserve is the gap between your resting heart rate and your estimated maximum. It is the working range your heart can use, and the Karvonen method sets training intensities as percentages of that reserve rather than of your maximum alone.
Find your heart rate reserve and three Karvonen targets.
max HR = 220 − age HRR = max HR − resting HR target at p% = (HRR × p) + resting HR
The reserve is only as good as the two numbers it comes from. Both maximum and resting heart rate are estimates here, so the targets are guideposts rather than exact prescriptions.
| Symbol | Meaning |
|---|---|
| age | Your age in years, used to estimate maximum heart rate. |
| resting HR | Your heart rate at rest, measured calmly. |
| percent | The share of reserve used for each target, here 65, 75, and 85 percent. |
At age 30 the maximum is about 190 bpm, so the reserve is 190 − 55 = 135 bpm. The 65 percent target is about 143 bpm, the 75 percent target about 156 bpm, and the 85 percent target about 170 bpm.
Heart rate reserve is the gap between your resting heart rate and your maximum, the span your heart can use during exercise. If your maximum is 190 and you wake at 60 beats per minute, your reserve is 130. The Karvonen method sets a target by taking a percentage of that reserve and adding it back to your resting rate.
For a target of 70 percent, you multiply 130 by 0.7 to get 91, then add the resting 60 for a target near 151 beats per minute. Notice this sits well above the 133 that a plain percent of maximum would give. The reserve method is more demanding because it measures effort relative to how much capacity you actually have.
Two people with the same maximum but different resting rates do not experience the same workout at the same absolute pulse. The fitter person, with the lower resting rate, has a larger reserve and reaches a given fraction of effort at higher beats. Ignoring resting rate hides that difference, which is why reserve based targets usually feel more accurate to trained athletes.
Continue with the Heart Rate Zones Calculator, Max Heart Rate Calculator, or the RPE Calculator — or browse more heart rate & performance tools and all sports calculators.
It measures how much your heart rate can rise above rest. A larger reserve usually reflects a lower resting rate, which often follows good aerobic fitness.
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Content updated: September 2026