Body Fat Calculator

The scientific name for body fat is "adipose tissue." Adipose tissue has several important roles. Its main function is to store lipids, which the body uses to produce energy. It also releases important hormones and gives the body both cushioning and insulation.

Body fat is made up of essential body fat and storage body fat. Essential body fat is the base amount of fat found throughout most of the body. It is the fat needed to sustain life and reproductive functions. The amount of essential fat differs between men and women, usually around 2–5% in men and 10–13% in women. The healthy body fat range for men is generally defined as 8–19%, while for women it is 21–33%. While having too much body fat can harm a person's health in many ways, having too little body fat can also have negative health effects. Keeping body fat below, or even at, the essential body fat range is something that should be discussed with a medical professional.

Storage fat is fat that builds up in adipose tissue, whether as subcutaneous fat (deep under the skin and around vital organs) or visceral fat (fat inside the abdominal cavity, between organs). When people talk about body fat, they usually mean this type. Some storage fat is normal and healthy, but too much of it can have serious negative health consequences.

Excess body fat leads to being overweight and eventually to obesity if steps are not taken to stop body fat from increasing. It is important to note that being overweight does not always mean having too much body fat. A person's body weight is made up of many factors, including (but not limited to) body fat, muscle, bone density, and water content. This is why highly muscular people are often classified as overweight.

The rate at which body fat builds up varies from person to person and depends on many factors, including genetics and behavioral factors such as lack of exercise and eating too much. Because of these varying factors, it can be harder for some people to lose fat stored in the abdominal area. However, managing diet and exercise has been shown to reduce stored fat. It is also worth noting that men and women store body fat differently, and this can change over time. After age 40 (or after menopause in some cases for women), lower levels of sex hormones can lead to extra body fat around the stomach in men, or around the buttocks and thighs in women.

The World Health Organization (WHO) considers obesity one of the leading preventable causes of death worldwide, estimated to cause 111,909 to 365,000 deaths per year in the U.S. This has become a growing concern because, according to the Centers for Disease Control and Prevention, 36.5% of U.S. adults are classified as obese.

Obesity is linked to a lower quality of life, worse mental health outcomes, obstructive sleep apnea, and several leading causes of death worldwide, including cardiovascular disease, stroke, certain cancers, and diabetes. All of these possible complications can shorten a person's life expectancy, which is why obesity is a medical condition studied by many researchers.

As mentioned earlier, fat produces several essential hormones that affect the body. Having too much or too little of critical hormones can have negative effects that prevent the body from functioning properly. Related to this, studies have found that excess body fat, especially abdominal fat, disrupts the normal balance and function of some of these hormones. In addition, body fat—specifically visceral fat—plays a role in releasing certain cytokines, which are a broad category of proteins involved in cell signaling, and these can potentially increase the risk of cardiovascular disease. Visceral fat is also directly linked to higher levels of low-density lipoprotein (LDL) cholesterol, lower high-density lipoprotein (HDL) cholesterol, and insulin resistance. LDL cholesterol is often called "bad cholesterol," while HDL is called "good cholesterol." High LDL cholesterol levels can clog arteries and lead to complications such as heart attacks. Insulin resistance means cells do not respond properly to the hormone insulin, which can lead to high blood sugar levels and eventually type 2 diabetes. As this shows, excess visceral fat can have measurable negative effects on a person's health.

U.S. Navy Method:

There are many specific techniques for measuring body fat. The calculator above uses a method based on equations developed at the Naval Health Research Center by Hodgdon and Beckett in 1984. The method for measuring the relevant body parts and the specific equations used are given below:

Measure the circumference of the subject's waist at a horizontal level around the navel for men, and at the level with the smallest width for women. Make sure the subject does not pull their stomach in, so the measurements are accurate.

Measure the circumference of the subject's neck starting below the larynx, with the tape sloping downward to the front. The subject should avoid flaring their neck outward.

For women only: Measure the circumference of the subject's hips at the largest horizontal measure.

Once these measurements are taken, use the following formulas to estimate body fat. Two equations are provided: one using the U.S. customary system (USC), which uses inches, and the other using the International System of Units, specifically centimeters:

USC Units:

BFP = 86.010 × log10(abdomen − neck) − 70.041 × log10(height) + 36.76

SI, Metric Units:

BFP = 495 / (1.0324 − 0.19077 × log10(waist − neck) + 0.15456 × log10(height)) − 450

Body fat percentage (BFP) formula for females:

USC Units:

BFP = 163.205 × log10(waist + hip − neck) − 97.684 × log10(height) − 78.387

SI, Metric Units:

BFP = 495 / (1.29579 − 0.35004 × log10(waist + hip − neck) + 0.22100 × log10(height)) − 450

Note that the results of these calculations are only estimates, since they are based on many different assumptions intended to apply to as many people as possible. For more accurate body fat measurements, instruments such as bioelectric impedance analysis or hydrostatic density testing are needed.

FM = BF × Weight

Lean Mass (LM) formula:

LM = Weight − FM

Another way to estimate body fat percentage uses BMI. Refer to the BMI Calculator to get an estimate of BMI for use with the BMI method, as well as more detail on how BMI is calculated, what it means, and its limitations. Briefly, estimating BMI involves formulas that require a person's height and weight. Given BMI, the following formulas can be used to estimate a person's body fat percentage.

Body fat percentage (BFP) formula for adult males:

BFP = 1.20 × BMI + 0.23 × Age − 16.2

Body fat percentage (BFP) formula for adult females:

BFP = 1.20 × BMI + 0.23 × Age − 5.4

Body fat percentage (BFP) formula for boys:

BFP = 1.51 × BMI − 0.70 × Age − 2.2

Body fat percentage (BFP) formula for girls:

BFP = 1.51 × BMI − 0.70 × Age + 1.4