Skip to content

Body Fat Calculator

Interactive Body Fat Calculator
Body Fat Calculator

The composition of the human body

More than 98% of the human body is composed of six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. Potassium, sulfur, sodium, chlorine, and magnesium are responsible for almost another 1%. These are the 11 most important, so called non-trace, elements. Regarding the molecules, the most common molecule in the human body is of course water, which takes about 65% of mass, followed by proteins and lipids. Other molecules which have a decent percent of mass are hydroxyapatite, carbohydrates and nucleic acids.

What is body fat?

It is actually adipose tissue; its main function is to store energy in the form of lipids, but it cushions and insulates your body, too. Your body stores two types of fat: essential and storage body fat. The former is necessary to support life and reproductive functions. Essential body fat is substantially higher for women because of childbearing and hormonal functions. Storage body fat is the mass of additional accumulated fat. It does not mean that this type of body fat is unnecessary, though – part of it protects your abdomen and internal organs.

How to calculate body fat?

You can estimate your body fat with our body fat percentage calculator. Remember that no calculator, however complicated, can replace a visit in a doctor’s office. You should treat this result as a rough estimate; it can only tell you if your body fat percentage is drastically too high, but there’s no reason to panic if the result differ slightly from the recommended value.

To calculate the body fat percentage, you need to take the following measurements:

  • Weight: simply weigh yourself. You will get the most accurate result weighing yourself in the morning, before breakfast, and without clothes on.
  • Waist: your waist is the narrowest part of your torso. The measuring tape you bring around your waist should sit tightly, but it shouldn’t “dig” into your skin. Don’t pull your stomach in, either.
  • Forearm: the forearm circumference is only needed to calculate the body fat of women. Put your tape around the thickest part of your forearm (close to your elbow).
  • Wrist: wrap a measuring tape around your wrist in the fullest part. Again, this measurement is not required for men.
  • Hip: you measure your hips it the widest point below your waist. Remember to remove your clothing and to keep your feet together so that the measurement is as accurate as possible. Men don’t need this measurement either for calculating the body fat percentage.

Once you have taken all of the measurements, you can input them all into the body fat calculator. If you are interested how it works, here are the formulas we use:

lean body mass (men) = (weight * 1.082) + 94.42 - Waist * 4.15

lean body mass (women) = (weight * 0.732) + 8.987 + wrist / 3.140 - waist * 0.157 - hip * 0.249 + forearm * 0.434

body fat weight = weight - lean body mass

body fat percentage (BFP) = body fat weight / weight

Both equations for lean body mass use weight in pounds and all other measurements in inches. If you are using other units, you can transform the formulas accordingly.

Is my body fat percentage normal?

Once you calculated your body fat percentage, you should compare it with the recommended values. The list below comes from the American Council on Exercise and shows the average percentages in specified groups.

  • Essential fat: 10–13% (women), 2–5% (men)
  • Athletes: 14–20% (women), 6–13% (men)
  • Fitness: 21–24% (women), 14-17% (men)
  • Average: 25–31% (women), 18–24% (men)
  • Obese: 32%+ (women), 25%+ (men)

This data means that if your body fat percentage is lower than 31% for women and 24% for men, you are in the average range and you have nothing to worry about. Higher levels of body fat may be dangerous for you.

The chart below shows the average body fat percentages of Americans from samples between 1999–2004. It is taken from the National Health and Nutrition Examination Survey in the United States.

Why should I control my body fat?

You need some body fat to regulate the production of hormones. An excessive percentage of body fat, however, can cause multiple health problems, such as:

  • Heart diseases: obesity and high levels of body fat can lead to high blood pressure and high levels of bad cholesterol, which are also risk factors for heart diseases. In extreme cases, they can lead to strokes, the third most common cause of death in the United States.
  • Male hormones problems: high body fat level in a woman’s body can lead to an excessive production of male hormones, causing facial hair growth and acne.
  • Diabetes: high body fat can lead to type 2 diabetes. There’s a strong correlation between diabetes and being overweight; people most at risk for developing type 2 diabetes are those who have a high body mass index (BMI) and a high body fat percentage.
  • Pregnancy complications: Women with high body fat levels are more likely to give birth prematurely or have children with health problems, including obesity. They are also more likely to need a Cesarean delivery.

Alternative methods of measuring body fat

If you type “how to calculate body fat” into your search engine, you will discover that there are multiple methods for measuring the body fat percentage. In fact, there are even multiple different formulas used in various calculators. The list below gives you some alternative methods.

  • Underwater weighing: fat cells in humans have a density of 0.9 kilograms per liter. The lean body mass has a higher density – 1.1 kg per liter. Knowing this difference, it is possible to determine the density of the whole body by submerging it in water. After making some corrections for air in lungs, you can calculate the percentage of body fat with only a small uncertainty.
  • Skinfold method: it is a method, in which you pinch your skin in several standardized places with calipers and measure the thickness of the fat layer. It requires from three to seven measurements. The drawback of this method is that it only measures the adipose tissue layer directly below the skin, and doesn’t take into account any internal body fat.
  • From BMI: there are some formulas that allow body fat percentage to be calculated directly from the BMI. They are not really accurate, though, as the amount of body fat for two people with the same BMI might be completely different.
  • Ultrasound: it can be used to measure tissue structure and hence the amount of adipose tissue directly below the skin.

How to reduce body fat?

Reducing body fat is not the same as losing weight. It’s not enough to lower your calorie intake and hope for the best. We listed a few basic rules for you, but remember that it is always better to contact a dietitian before starting any diet.

  • Go for long-term: you should plan losing your body fat in long term, starting with some moderate exercises and gradually increasing their intensity. If you are really obese, you should begin with the basic exercise of walking.
  • Do both weight lifting and cardio exercises. Varying your exercises will keep your body from adapting and will cause faster loss of body fat.
  • Plan a good diet that includes less saturated fats. You still need some fats, though, but try to settle for oils instead. You can read more about a balanced diet in the description of our calorie calculator.
  • Do not overextend! You may end up hurting yourself if you eat too little. Our BMR (Basal Metabolic Rate) calculator will tell you what the minimum number of calories are for your body to survive. You cannot eat less than that! You still have to add a number of calories spent during your daily activity. Remember, reducing weight is a long-term process.
  • Drink lots of water. If you exercise a lot, you lose water first, so it’s a good idea to keep yourself hydrated. You can drink tea, too.
  • Pick proper snacks. Never go for sweets, candy bars or other high-fat snacks. Choose fruit and vegetables instead.
  • Never settle for a “miracle diet” plan you found somewhere in internet. It may be totally unbalanced and dangerous for your health!
  • Plan some “cheat days” in advance, for example family gatherings. You probably won’t be able to avoid that second serving, so it’s better to plan it rather than feel guilty about it.

Is fat so bad?

Reading all that things you may start to think; “fat is bad and it would be the best to have non of it at all.” But is that really true? Let me give you examples!

Andreas Münzer was an Austrian professional bodybuilder. In his preparation and training he used multiple ergogenic acids, steroids, diuretics. He was known for his extremely low body fat levels. Unfortunately, his drug taking lead to complications, and he developed upper gastrointestinal track bleeding, which caused his death, because he had no fat to cope with the medical stress after the surgery.

However, no body fat happens not only to bodybuilders. Lizzie Velásquez is a famous American motivational speaker and YouTuber. She suffers from extremely rare congenital disease called Marfanoid–progeroid–lipodystrophy syndrome. One of its symptoms is preventing body from accumulating fat tissue and gaining weight, what causes that such patients have zero percent of body fat. She has never weighed more than 29 kg and is required to eat about 8000 calories daily!

As you can see, fat is not all bad, excess fat is bad!


For women, a body fat range of 13-31% is considered healthy, while for men the range is 5-24%. Body fat is not the most accurate measure of health however, and it becomes more acceptable to have more body fat the older you are, due to your metabolism slowing.

Fat leaves the body primarily through the lungs when you exhale. This is because when fat is used as an energy source, the reaction uses oxygen to produce energy and carbon dioxide. The CO2 then enters the blood, ending up in the lungs. Fat is also leaves via sweat, urine and feces.

When you need to use your stored fat for energy, your body begins releasing fatty acids into the blood. Here they are transported around the body to the muscles in need. Once in the muscles, they are broken down, releasing energy and CO2. The CO2 then leaves the body through the lungs or urine.

Fats are an essential part of our diet; they provide us with energy, are used in cell growth, and are made into essential hormones. Fatty tissues protect our organs from physical damage,and provide us with insulation. Too many fatty tissues will act as new pathways for diseases to form.

Body fat scales can be very accurate, but due to the number of factors affecting the reading, expect the result to be off by about 5% for the best scales on the market. To maximize their accuracy, follow their instructions as closely as possible.

Yes, body fat scales do work, and have an accuracy of around 95%, depending on the model. They work by passing a harmless electric current round your body and measuring the resistance. They are, however, very dependent on body water content, so follow the instructions carefully.

  • Skinfold calipers.
  • Dual-energy X-ray Absorptiometry (DXA).
  • Hydrostatic weighing.
  • Bioelectrical Impedance Analysis (BIA).
  • Body circumference measurements.
  • In the USA, the average body fat percentage between 1999-2004 for a woman aged 16-19 was 35%, for those 20-39 it was 38%, and for those 40-59 it was 41%. For men between 16-19 it was 23%, between 20-39 it was 26% and between 40-59 it was 28%.
  • Losing anywhere between 1 – 3% of your body fat per month is considered to be both healthy and achievable. This is, however, not certain as fat loss depends on a lot of different factors, so please consult with your doctor or dietitian before losing a large amount of weight.
  • Your body burns fat when there is not enough energy in your bloodstream to meet the requirements of your current needs. If you have just eaten, you body will use up that energy before burning through fat. Also, if you have no fat to burn, the body will burn muscle instead.