Calculate heart rate reserve from maximum and resting heart rate, then build Karvonen target ranges across five training zones.
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. If maximum heart rate is blank, this calculator uses the Tanaka estimate: 208 – 0.7 x age.
Karvonen intensity bands used by this calculator
| Reference | Range or value | Use or interpretation |
|---|---|---|
| Zone 1 | 50-60% HRR | Easy recovery and warm-up work |
| Zone 2 | 60-70% HRR | Steady aerobic work |
| Zone 3 | 70-80% HRR | Moderate to vigorous work |
| Zone 4 | 80-90% HRR | Hard threshold-oriented work |
| Zone 5 | 90-100% HRR | Very hard, short efforts |
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.