Heart Rate Reserve Calculator (Karvonen Method)

The Karvonen method sets the training heart rate from the heart rate reserve rather than from maximum heart rate alone. The formula is: target = resting heart rate + intensity percent * heart rate reserve. Including the resting rate personalises the zones better than a plain percentage of HRmax.

Heart rate reserve is the difference between maximum and resting heart rate: HRR = HRmax - resting heart rate. It shows how many beats per minute the heart can speed up from rest to maximal effort. The larger the reserve, the more room to adjust training intensity.

It uses the Fox formula: HRmax = 220 - age. It is simple and popular but only an estimate. The Tanaka formula (208 - 0.7 * age) is often closer for older people. The most reliable HRmax measurement comes from an exercise stress test.

Warm-up and recovery suit 50–60% of reserve, aerobic endurance 60–70%, fitness improvement 70–80%, and high-intensity intervals 80–90% and above. Beginners should start lower and increase intensity gradually as fitness improves.

A plain percentage of HRmax ignores fitness, computing the rate as a share of HRmax alone. Karvonen adds the resting rate and works on the reserve, so for the same intensity it usually gives a higher and more realistic target heart rate.

Best in the morning, just after waking, while still lying down. Count beats for a full minute or use a sports watch or band. Adults typically read 60–80 bpm, well-trained people even below 50 bpm. Accurate measurement directly affects the result.

A lower resting rate means a larger reserve, because the gap between HRmax and rest grows. In the Karvonen method the target depends on the reserve, so for the same intensity a larger reserve yields a higher training heart rate. A low resting rate usually signals good cardiac fitness.

Yes, the method works regardless of discipline because it relies on heart rate. Note that maximum heart rate tends to be slightly lower in cycling than in running. For cycling training some combine heart rate zones with power zones from a power meter.

Not for everyone. Healthy people can increase intensity gradually, but those with heart disease, hypertension, after procedures or taking heart-rate-affecting medications (e.g. beta-blockers) should consult a doctor before intense effort, as such drugs can markedly lower heart rate.

No. It gives indicative values based on estimation formulas and is meant for recreational training planning. It does not replace fitness testing or an individual training plan. For serious sport or health issues, use an exercise test and consult a specialist.