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Karvonen Heart Rate Calculator (%HRR)
Calculate your training zones the Karvonen way — using your heart-rate reserve rather than a flat percentage of max HR. The Karvonen formula is target = ((max HR − resting HR) × %) + resting HR, so it factors in your resting heart rate and gives more personalised zones that correlate a little better with %VO₂max. Enter your age and resting HR: the calculator estimates max HR with the research-validated Tanaka equation (208 − 0.7 × age, not the age-biased 220 − age), then shows every zone both by Karvonen (%HRR) and by %HRmax side by side. For a 40-year-old with a resting HR of 60, heart-rate reserve is 120 bpm, so Zone 2 (60–70%) by Karvonen is about 132–144 bpm — roughly 20 bpm higher than the 108–126 bpm you would get from %HRmax. That gap is exactly why the two methods must not be conflated. This is a fitness estimate — max HR varies ±10–12 bpm between individuals, so treat the numbers as guidance and use a test or wearable for your true zones.
Karvonen: target = ((max HR − resting HR) × %) + resting HR
- Age 40, resting HR 60 → HRR 120 bpm, Zone 2 ≈ 132–144 bpm
- Karvonen zones run ~20 bpm above %HRmax — both shown side by side
Frequently asked questions
What is the Karvonen formula?
The Karvonen formula computes a target heart rate as ((max HR − resting HR) × intensity) + resting HR. The (max HR − resting HR) term is your heart-rate reserve. Because it adds resting HR back in, Karvonen zones sit higher than plain %HRmax zones and are more personalised to you.
Why are my Karvonen zones higher than %HRmax zones?
Karvonen works from your heart-rate reserve and adds your resting HR back on top, so its targets land higher than a flat percentage of max HR. For a 40-year-old with a resting HR of 60, Zone 2 is about 132–144 bpm by Karvonen versus 108–126 bpm by %HRmax — around a 20 bpm difference.