Karvonen Calculator

The Karvonen formula is widely considered the most individualized way to set heart-rate training zones because it factors in your resting heart rate, not just your age. Instead of taking a flat percentage of your maximum, it works from your heart-rate reserve — the room between rest and max — which reflects how fit you actually are. This calculator applies the Karvonen method to your numbers so your zones match your physiology rather than a generic average.

The Karvonen Formula

The piece in parentheses, Max HR − Resting HR, is your heart-rate reserve (HRR). You take the chosen fraction of that reserve and then add your resting heart rate back on top. The "+ Resting HR" step is what makes Karvonen different from a plain percent-of-max calculation.

What Heart-Rate Reserve Means

Two people can share the same max HR but have very different resting rates. A trained endurance athlete might rest at 45 bpm while a sedentary person rests at 75 bpm. The athlete has a far larger heart-rate reserve to work with, and Karvonen captures that, producing zone targets tailored to each person rather than treating them identically.

Worked Example

Consider a 30-year-old with a resting heart rate of 60 bpm, training at 70% intensity:

• Max HR = 220 − 30 = 190 bpm
• Heart-rate reserve = 190 − 60 = 130 bpm
• Target = (130 × 0.70) + 60 = 91 + 60 = 151 bpm

For comparison, the plain percent-of-max method gives 190 × 0.70 = 133 bpm. Karvonen returns a higher target (151 bpm) because it accounts for the resting heart rate sitting underneath the workload.

Karvonen Zones for This Example

Using Max HR 190, Resting HR 60 (reserve = 130 bpm):

Why Karvonen Is More Individualized

• It rewards fitness. A lower resting heart rate widens your reserve and shifts your zones, so as you get fitter your targets adjust with you.
• It tracks effort more closely. Heart-rate reserve correlates well with the percentage of oxygen uptake you are using, so zones map more cleanly onto physiological strain.
• It avoids the floor problem. Percent-of-max can set "easy" zones below your actual resting rate for very fit people; Karvonen never does.

How to Measure Your Resting Heart Rate

Karvonen is only as good as your resting heart-rate number, so measure it carefully:

• Measure first thing in the morning, before getting out of bed, while still calm.
• Count for a full 60 seconds, or use a wearable that logs overnight resting rate.
• Average several days. A single reading can be thrown off by a poor night's sleep, caffeine, or stress.
• Re-test periodically. As your fitness changes, so does your resting rate — and therefore your zones.

Note: This calculator is for general fitness and informational purposes only and is not medical advice. It relies on an estimated maximum heart rate that can vary by ±10–12 bpm. If you have a heart condition or take medication affecting heart rate, consult a healthcare professional before training to these targets.