Karvonen, moderate intensity
A 35-year-old with a 65 bpm resting heart rate, targeting moderate intensity (70–80%), gets a target range of 149–161 bpm.
Target heart rate calculator
This is an estimate for information only. It is not medical advice — check with a healthcare professional before starting a new exercise program, especially with a pre-existing heart condition.
Result
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How it works
Both methods start from an estimated maximum heart rate (220 minus age, a widely used approximation). The straight-percentage method applies the target intensity directly to that maximum. The Karvonen method instead works with heart rate reserve — the gap between resting and maximum heart rate — which accounts for fitness level: two people with the same age and max heart rate but different resting rates get different target zones.
The five zones shown span very light activity through maximum effort, so you can see how the target range shifts with intensity, not just at the one level you picked.
Formulas used
Karvonen method
Target HR = Resting HR + Intensity × (Max HR − Resting HR)
Straight percentage method
Target HR = Intensity × Max HR
Worked examples
The simpler straight-percentage method, same person
The same 35-year-old using the straight-percentage method instead gets a slightly different range: 130–148 bpm for moderate intensity.
Assumptions and limits
- Maximum heart rate is estimated as 220 minus age — an approximation, not a measured value.
- Resting heart rate is assumed accurate and measured under calm, rested conditions.
Frequently asked questions
Why do the two methods give different results?
The Karvonen method effectively raises the target range for someone with a lower (fitter) resting heart rate, since it scales the intensity against heart rate reserve rather than the raw maximum.
How accurate is "220 minus age"?
It is a population average with a fairly wide individual spread — actual maximum heart rate can differ from the estimate by 10–20 beats per minute for some people. A supervised maximal exercise test gives a more precise number if needed.
What intensity should I train at?
It depends on your goals: lighter zones are often used for recovery or building an aerobic base, while harder zones target performance gains — many training plans mix zones across the week rather than staying in one.
How do I find my resting heart rate?
Measure your pulse for a full minute right after waking up, before getting out of bed, ideally averaged over a few mornings for a stable reading.
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