How this calculator works
A common training zone is 60 to 80 percent of maximum heart rate. The simple method multiplies the maximum by 0.60 and 0.80. The Karvonen method instead works from heart rate reserve, which is maximum minus resting, and adds the chosen percentage of that reserve back to the resting rate. Karvonen accounts for fitness because a lower resting heart rate produces a higher target for the same percentage. The age formula 220 minus age is a population average with a standard deviation of about 10 to 12 beats per minute; a measured maximum from a supervised test is better. The idea that low-intensity exercise burns a higher proportion of fat is true, but total energy use matters more for fat loss. A harder session burns more total calories even though the fat share is lower.
Formula
Estimated maximum = 220 - age. Heart rate reserve = maximum - resting. Percent-of-maximum zone: lower = 0.60 x maximum, upper = 0.80 x maximum. Karvonen zone: lower = resting + 0.60 x reserve, upper = resting + 0.80 x reserve.
Worked example
A 40-year-old with a resting heart rate of 60 has an estimated maximum of 180 and a reserve of 120. The 60 to 80 percent zone is 108 to 144 beats per minute, while the Karvonen zone is 60 + 0.60 x 120 = 132 to 60 + 0.80 x 120 = 156. With a measured maximum of 185, the Karvonen zone becomes 135 to 160.
Advertisement
Frequently asked questions
Which zone method should I use?
Use Karvonen if you know your resting heart rate, because it adjusts for fitness. Use percent of maximum if you only have an age estimate and want a simple range.
Is the fat burning zone the best zone for weight loss?
Not for total energy. The body uses a higher proportion of fat at low intensity, but a harder workout burns more calories overall and usually more fat in absolute terms. Diet and total energy balance dominate.
Can I use this without a heart rate monitor?
You can use the numbers as a guide, but checking your pulse during exercise is less reliable than a chest strap or wrist monitor. Stop if you feel dizzy or unwell.