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Body Fat Calculator

Reviewed by BS Raquel Mendoza Hernández

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Table of Contents

How to Use the Body Fat Calculator

To use our online simulator, simply enter the data requested in their respective forms.

First, enter your height in centimeters; second, your weight in kilograms; third, your waist width in centimeters; fourth, your neck width in centimeters; fifth, choose your gender; finally, choose your level of physical activity.

Once you have entered all the data, click on “Calculate” and our tool will do the rest, giving you the estimated result in a matter of seconds.

What is Body Fat Percentage

When referring to body composition, we are talking about the elements that make up our body. The most present component is water, accounting for 50 to 65% of the weight.

In addition to water, our body also contains bones, muscles, and fats. These three components vary in weight according to age, gender, and physical activity. (1)

The assessment of body fat has been used to measure the risks of developing coronary diseases such as hypertension or heart attacks, or metabolic diseases like diabetes. The higher the percentage, the greater the risk of illness.

Women have a higher percentage of fat than men, and both genders tend to lose muscle and gain fat as they age.

Adipose tissue or body fat is a tissue for energy storage, but also for the production of hormones involved in the regulation of metabolism.

This tissue is located in two major areas: subcutaneous fat, which is found beneath the skin, and visceral fat, which supports and protects the internal organs.

The amount and percentage of body fat depend on various factors such as age, gender, sports practice, the presence or absence of metabolic diseases, among others.

Men tend to accumulate fat in the abdominal area and back, while women have a greater accumulation in the lower part such as hips and thighs.

This distribution of fat has led to the classification of body types into two somatotypes: android or apple-shaped in the case of men, and gynoid or pear-shaped in women.

The former may represent a higher risk for developing some cardiometabolic diseases. (2)

Below we offer you a table that can serve as a reference to know the recommended body fat values by age and gender, based on the classification by Gallagher (2000): (3)








< 21%



> 39%





> 40%


< 24%



> 42%








< 8%



> 25%





> 27%


< 13%



> 30%

Source: Gallagher et al. Am J Clin Nut 2000:694-701

If you practice sports that require significant modifications in body fat values, this table will not be useful, as it was designed using sedentary or lightly active population as a reference.

On the other hand, if you want to calculate the body fat percentage from home, in a manual and more reliable way, keep reading and learn how to do it.

How to Calculate Body Fat Percentage at Home

There are many ways to calculate body fat, from the most traditional methods to the most innovative, such as laser scanning of your entire body.

However, calculating body fat can even be done at home, with quite reliable results, but if you want to achieve maximum reliability, you will need the help of specialists with the appropriate instruments.

To start, you will need to calculate your Body Mass Index (BMI), which will be really practical to know if you are above your ideal weight. You just need to know your height and weight, the result will give you an approximation of how much fat is in your body.

If you want to know this data, you simply have to divide (in kg) by your height squared (in meters). A higher result means a greater probability of suffering from a disease.

The common BMI is between 18 and 24; if, on the other hand, you are between 25 and 30, it means you are overweight, while a value above 30 indicates obesity and a high risk of cardiovascular disease.

This operation works for most people, but it has some limits: it tends to overestimate athletes, and, on the other hand, underestimate the amount of fat present in the bodies of the elderly and those who, for whatever reason, have decreased their muscle mass.

You can find a much more accurate BMI calculation method, through this equation:

  • (1.20 * BMI) + (0.23 * age) – (10.8 * gender) – 5.4
  • The variable gender should be replaced by 1 if you are male and by 0 if you are female.

Secondly, measure your waist. The circumference of your belly can help you recognize if you have any problems derived from obesity or overweight.

More specifically, if the largest amount of fats are located in the abdomen rather than the sides, the probability of suffering from cardiovascular diseases increases.

To measure your waist correctly, stand up without wearing clothes and place the tape measure around the lower part of the abdomen, then measure the volume of your waist after fully exhaling.

Remember to place the tape measure so that it is as close to the skin as possible and fits the shape of your abdomen, but without exaggerating and pressing too much.

There are several referential sources to classify the value of abdominal circumference. (4)

The Adult Panel Treatment III


Abdominal Obesity


> 80 cm


> 94 cm

The International Diabetes Federation (IDF)


Abdominal Obesity


> 80 cm


> 90 cm

World Health Organization (WHO)


Low Risk

Increased Risk

High Risk


< 79 cm

80-87 cm

> 88 cm


< 93 cm

94-101 cm

> 102 cm

Thirdly, use a skinfold caliper to know the body fat. This type of test aims to evaluate body composition and corroborate the efficiency and effectiveness of the different equations existing according to the number of data taken. (5)

These values will then need to be transformed to approximate the body fat percentage through an operation. Some of these operations require only 3 measures, others, however, need up to 7. While skinfold measurement does not reveal a 100% exact percentage, it is, nevertheless, a reliable way to know how the composition of our body changes over the days, which is why it is important to perform it several times on the same part of the body and with the same instrument. You should find a professional or someone qualified in skinfold measurement, as only by doing it this way can precise data be guaranteed. The approximations to body weight that are based on this method, and especially its effectiveness, depend both on the instrument and the operator's technique. This examination, on the other hand, only takes into consideration one type of fat, the one that is found beneath the skin Fourthly, you can also calculate bioelectrical impedance, the bioelectrical impedance analysis method offers a way to perform an anthropometric assessment that is non-invasive, it has been very useful for conducting research as well as for personalized patient care. (6) By employing this type of techniques, you will be measuring the difference between the levels of electrical fluidity between common tissues and fat. It has been said that this novel method has an accuracy of up to 95%. Another advantage is that it can be performed without the presence of qualified personnel and the devices you will need are accessible, a large part of gyms and physiotherapy clinics have one available for their clients. If you want to get more accurate results, it is advisable not to ingest liquids, 4 hours before testing; also, do not perform heavy physical activities in the 12 hours prior.

Some practical advice

Some research laboratories and sports medical clinics use air plethysmography to determine the composition of the human body by measuring air movement. The basic concept is similar to that of hydrostatic weight. However, it is a method more adapted to measure the body composition of the elderly, obese people, and people with some type of physical disability, ensuring high levels of accuracy. However, it is difficult to find a place that uses this technology. On the other hand, if your BMI is over 25, ask your doctor for advice or strategies to lose weight and thus reduce the risk of cardiovascular problems. In this article, you have learned how to use the body fat calculator and how to do it manually with up to 4 different methods, each with a higher level of precision. If you liked the article and found it provided useful information, do not hesitate to share it on social networks, so all your contacts can measure the percentage of fat in their body and prevent possible cardiovascular diseases. Finally, if you find any programming error in the online calculator or typos in the explanation on how to calculate body fat index, you can contact us through the contact page, so you will help us locate and correct them as quickly as possible, thus contributing your bit to this project of free calculators and simulators.

Bibliographic resources

  1. Ángeles Carbajal Azcona. Body Composition. Department of Nutrition. Faculty of Pharmacy. Complutense University of Madrid. Available at:
  2. Rebato E. Growth: a vision from Physical Anthropology. Rev Esp Antrop Fís. 2010; (31): 85-110. Available at:
  3. E. Jones W. Body Fat Percentage: Do You Know Yours? [Internet]. GenetiHealth. 2011. Available at:
  4. Tarqui-Mamani Carolina, Alvarez-Dongo Doris, Espinoza-Oriundo Paula. Cardiovascular risk according to abdominal circumference in Peruvians. An. Fac. med. 2017 Jul; 78(3): 287-291. Available at:
  5. Lopategui Corsino E. Evaluation of body composition: estimation of the percentage of fat with the skinfold or subcutaneous folds method [Internet]. Human movement and health sciences. 2002. Available at:
  6. Espinosa-Cuevas María de los Ángeles, Rivas-Rodríguez Lucía, González-Medina Enna Cristal, Atilano-Carsi Ximena, Miranda-Alatriste Paola, Correa-Rotter Ricardo. Bioelectrical impedance vectors for body composition in Mexican population. Rev. invest. clín. [journal on the Internet]. 2007; 59(1): 15-24. Available at:
BS Raquel Mendoza Hernández
Bachelor's degree in Nutrition and Dietetics from UCV. Postgraduate diploma in Public Management in Nutrition from UBV.
Raquel Mendoza Hernández holds a degree in Nutrition and Dietetics from the Central ... Read more »

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