Calculate heart rate reserve (HRR) from your age or known maximum heart rate and resting heart rate, with Karvonen target heart rate ranges.
Heart Rate Reserve and the Karvonen Formula
Heart rate reserve (HRR) is the difference between maximum heart rate and resting heart rate. The Karvonen method adds a selected percentage of that reserve back to resting heart rate, so two people with the same maximum heart rate can receive different targets when their resting heart rates differ.
Formula and Method
HRR = maximum heart rate – resting heart rate. Karvonen target heart rate = resting heart rate + intensity fraction x HRR. Select the age-estimate mode to use Tanaka: 208 – 0.7 x age. Estimates are limited here to ages 18–81, the laboratory validation range; the equation describes healthy adult population averages.
Illustrative Karvonen bands used by this calculator. These ten-percentage-point bands are a convention, not measured physiological or safety thresholds. Rounded endpoints can overlap.
| Reference | Range or value | Use or interpretation |
|---|---|---|
| Zone 1 | 50-60% HRR | Illustrative percentage band; individual thresholds differ |
| Zone 2 | 60-70% HRR | Illustrative percentage band; individual thresholds differ |
| Zone 3 | 70-80% HRR | Illustrative percentage band; individual thresholds differ |
| Zone 4 | 80-90% HRR | Illustrative percentage band; individual thresholds differ |
| Zone 5 | 90-100% HRR | Illustrative percentage band; individual thresholds differ |
How to Use the Result
Use a calm resting pulse measured under repeatable conditions. A tested maximum heart rate is more individual than an age equation, but testing should match your health and training context. Keep the same method when comparing sessions.
Assumptions and Limitations
Age equations describe population averages and can miss an individual’s true maximum by a meaningful amount. Medications, illness, heat, dehydration, altitude, fatigue, and measurement error can shift heart rate. Training zones are planning ranges, not diagnostic thresholds.
Sources
- Karvonen MJ, Kentala E, Mustala O. The effects of training on heart rate, 1957.
- Tanaka H, Monahan KD, Seals DR. Age-predicted maximal heart rate revisited, 2001.
