Enter your age into the calculator below to determine the minimum heart rate you must be at while exercising to maximize fat burn.

Fat burning zone formula

The formula for your maximum heart rate is mostly dependent on age and can be calculated with one of the following:

  • 191.5 – .007 x age^2 = MHR
  • 201 – .63 x age for women = MHR
  • 206.9 – (o.67 x age) = MHR
  • 208 – (0.7 x age) = MHR

The formula for determining the fat-burning zone is very straightforward. The fat-burning zone starts at 85% of your maximum heart rate. The higher that percentage goes, the more fat your will be burning.

Your max heart rate will vary depending on which of the equations is used, but it should not vary more than 5%.

What is the fat burning zone?

The fat-burning zone is a term used in the fitness and health industry to describe the heart rate at which the human body starts to consume fat for energy. This is typically a result of extended periods of exercise at a high intensity.

It’s believed that after a certain heart rate the human body switches to burning fat instead of stored glycogen stores in the muscles. This is because at high heart rates and intense exercise the body cannot consume enough energy only from glycogen stores in the muscle. This results in the activation of the fat burner.

This understanding and science is the basis of the new fitness trend of high-intensity interval training, also known as HIIT. This training involves working in intervals of very high effort and heart rate, followed by short or equal periods of rest. The idea behind this type of training is that the human body can only stay in the max effort range of exercise, 90+% of max heart rate, for more than 2-3 minutes. So instead, this interval training puts you in that zone for 60-90 seconds, then gives you a break, then repeats. You do this enough times and by the end of the workout, you’ve spent 15+ minutes in the fat-burning zone.

fat burning zone calculator