How to Calculate Your Fat-Burning Heart Rate Zone

The fat burning zone is a heart rate achieved during exercise that is considered most ideal for fat loss. It is estimated to be between 64% to 76% of your maximum heart rate, but can vary depending on your age, diet, and fitness level.

Take, for example, a 40-year old person swimming laps. The maximum heart rate for people in this age group is 180 beats per minute (bpm). To improve their fitness and burn excess fat, the swimmer should try to keep their heart rate between about 115 bpm and 137 bpm throughout their session.

This article explains what the fat burning zone is and why it's important. It provides charts and equations to help you find your maximum heart rate and fat burning zone, along with exercise ideas for getting the best results.

woman exercising on treadmill

Jose Luis Pelaez Inc. / Getty Images

The Fat Burning Zone Theory

The concept of a fat burning zone (sometimes called the temperate zone) comes from the theory that different heart rate intensities require the body to burn fuel from different sources.

According to the fat burning zone theory:

  • Fat burning is limited during higher-intensity exercise, such as sprinting and interval training.
  • Lower-intensity exercises may be the most optimal for burning fat.

The average resting heart rate for adults—that is, your heart rate when you're not active—is 60 to 100 bpm. When you exercise, your heart rate quickens as your heart pumps more oxygen-rich blood to your muscles. In order to sustain this elevated heart rate, your body burns fuel to make energy.

Specifically, research shows that when the heart beats between 64% to 76% of its maximum rate, the body burns fat as its primary fuel source. This is a relatively low heart rate; many people can even continue to talk at this intensity.

Once heart rate surpasses this range, however, the body's primary fuel source becomes carbohydrates.

Fat Burning Zone vs. Cardio Zone

The primary difference between the fat-burning zone and the cardio zone is the intensity of the exercise. For cardio benefits, your heart rate can increase to about 85% of its maximum, but it only needs to increase to around 64% to 76% of its maximum to burn fat.

Burning Calories vs. Burning Fat

Any form of exercise requires energy and will, therefore, burn calories.

However, while the proportion of fat used for energy may be higher with a low-intensity cardio exercise like walking, it will take much longer to burn as many calories performing this exercise as compared to a high-intensity exercise like a vigorous run.

Calculating Your Fat Burning Zone

You need to use two equations to figure out your fat burning zone. The first will give you the lower end of your fat burning zone. The second will give you the higher end of that range.

  • Maximum heart rate for your age x .64 = lower end of fat burning zone
  • Maximum heart rate for your age x .76 = higher end of fat burning zone

Determining Your Maximum Heart Rate

Maximum heart rate is the fastest your heart can beat per minute, typically during exercise or periods of high stress. As you can see in the above equations, you will need this number to determine your fat burning zone.

There is some debate among experts regarding how best to calculate maximum heart rate. One way is the Fox formula. While useful, it doesn't account for many individual differences that can influence your maximum heart rate, particularly your sex and fitness level.

Still, it is the recommended method of the American Heart Association. The Fox formula is as follows:

  • 220 - your age = maximum heart rate
 Age  Maximum Heart Rate
 20 years  200 bpm
 30 years  190 bpm
 35 years  185 bpm
 40 years  180 bpm
 45 years  175 bpm
 50 years  170 bpm
 55 years  165 bpm
 60 years  160 bpm
 65 years  155 bpm
 70 years  150 bpm

Fat Burning Zones By Age

The following chart lists fat burning zones by age group. If you don't want to do the specific calculations above, this can give you a general sense of where you need to be to burn fat.

 Age Estimated Fat Burning Zone
20 years 128-152 bpm
30 years 122-144 bpm 
35 years 118-141 bpm
40 years 115-137 bpm
45 years 112-133 bpm
50 years 109-130 bpm
55 years 106-125 bpm
60 years 102-122 bpm
65 years 99-118 bpm
70 years 96-114 bpm

Monitoring Heart Rate During Workouts

Many treadmills, elliptical machines, and other cardio equipment have special sensors that you can use to see your heart rate.

Other wearable devices, like heart rate monitors and smartwatches, can provide information on heart rate and track your readings over time.

Exercises for Fat Burning

Energy sources for exercise vary based on the intensity of the activity. At lower levels of activity, the proportion of energy derived from fat is higher.

Some examples of lower-intensity exercise include:

  • Walking
  • Cycling
  • Swimming

If you're not sure whether an activity qualifies as low-intensity, you can do the talk test, also called perceived rate of exertion. Most people can talk and sing during low-intensity activity. If you can talk but you can't sing, then the activity can be considered moderate intensity.

During high-intensity activity, most people aren't able to get through a whole sentence without stopping to take a breath.

If your goal is fat burning, try to find a low-intensity exercise that you find enjoyable and can do consistently on most days of the week.

Recommended Exercise

The AHA recommends getting at least 150 minutes of exercise a week, but adding any amount of physical activity to a sedentary lifestyle is beneficial to your overall health.

Other Considerations When Trying to Lose Weight

While reaching your fat-burning heart rate sounds like the way to lose weight, it's not the only consideration.

  • Caloric intake. Caloric intake depends mainly on the consumption of macronutrients, like fat, carbohydrates, protein, and more. These contain variable amounts of calories per gram, ranging from 4 to 9 calories/gram.
  • Insoluble fiber. Fiber also plays a role in caloric intake, since insoluble fiber is not absorbed. Insoluble fiber adds bulk to what you eat, which can make you feel fuller. It does not, however, contribute to your caloric intake since it isn't digested.
  • Gut microbiome and health conditions. Studies have also looked at the role of the gut microbiome—the microorganisms, including bacteria and viruses, in the gastrointestinal tract)—in weight loss and metabolism, as well as the number of health conditions a person has.
  • Metabolic rate. Your body requires a significant amount of energy for basic processes like heartbeats and breathing to take place—even when you're resting. This is known as the resting metabolic rate. Any exertion beyond that burns more calories.

Summary

Fat-burning heart rate is based on the idea that the body gets energy for physical activity by burning fat only when you are working out at specific intensity levels.

While higher-intensity exercises burn more calories, lower-intensity exercises burn more fat.

Your fat-burning heart rate is calculated based on your age and maximum heart rate.

Frequently Asked Questions

  • What types of exercises burn the most fat?

    It's actually lower-intensity exercises that burn more fat. Examples include cycling, swimming, and walking. However, it will take a lot longer to burn the same amount of calories at a low-intensity exercise compared to a more vigorous activity like running.

  • How long should you exercise in the fat-burning zone?

    The AHA recommends getting a minimum of 150 minutes of moderate-intensity exercise each week. Five days of exercise a week with 30 minutes spent in the fat-burning zone each day will accomplish the minimum recommendation. Doubling that provides even more benefits.

7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. American Heart Association. Target heart rates chart.

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  4. Lach J, Wiecha S, Śliż D. HR max prediction based on age, body composition, fitness level, testing modality, and sex in physically active population. Front Physiol. 2021 Jul;12(1):1-9. doi:10.3389/fphys.2021.695950

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By Angela Ryan Lee, MD
Angela Ryan Lee, MD, is board-certified in cardiovascular diseases and internal medicine. She is a fellow of the American College of Cardiology and holds board certifications from the American Society of Nuclear Cardiology and the National Board of Echocardiography. She completed undergraduate studies at the University of Virginia with a B.S. in Biology, medical school at Jefferson Medical College, and internal medicine residency and cardiovascular diseases fellowship at the George Washington University Hospital. Her professional interests include preventive cardiology, medical journalism, and health policy.