Body Fat Calculator
A body fat calculator is a tool used to estimate the amount of body fat a person has based on their weight, height, age, and gender. There are several methods to calculate body fat percentage, including skinfold measurements, bioelectrical impedance analysis, and hydrostatic weighing.
One commonly used method is the Body Mass Index (BMI) calculation, which is based on an individual’s weight and height. BMI is calculated by dividing a person’s weight in kilograms by their height in meters squared. The resulting number is used to determine whether an individual is underweight, normal weight, overweight, or obese. However, BMI doesn’t directly measure body fat percentage and can sometimes be inaccurate, especially in athletes or people with a lot of muscle mass.
Another method is skinfold measurements, which involves using calipers to measure the thickness of skinfolds in different areas of the body. This measurement is used to estimate the amount of subcutaneous fat beneath the skin. Bioelectrical impedance analysis involves passing a small electrical current through the body and measuring the resistance to the current, which can then be used to estimate body fat percentage. Hydrostatic weighing involves submerging an individual in water and measuring their body density, which can then be used to calculate body fat percentage.
It’s important to note that body fat percentage can vary widely depending on factors such as age, gender, genetics, and lifestyle. While a body fat calculator can provide an estimate, it’s best to consult with a healthcare professional for a more accurate assessment of your body fat percentage and overall health.
Using certain measurements, the body fat calculator can give you an idea of how much fat is in your body. If you are more familiar with the International System of Units, click on the “Metric Units” tab (SI). For best results, measure to the nearest 1/4 inch (0.5 cm). This calculation is based on the U.S. Navy method, but the BMI method is also used to figure out how much body fat a person has (both of which are outlined below).
Reference
The American Council on Exercise’s Body Fat Categorization
| Description | Women | Men |
| Essential fat | 10-13% | 2-5% |
| Athletes | 14-20% | 6-13% |
| Fitness | 21-24% | 14-17% |
| Average | 25-31% | 18-24% |
| Obese | 32+% | 25+% |
Jackson and Pollard’s Ideal Body Fat Percentages
| Age | Women | Men |
| 20 | 17.7% | 8.5% |
| 25 | 18.4% | 10.5% |
| 30 | 19.3% | 12.7% |
| 35 | 21.5% | 13.7% |
| 40 | 22.2% | 15.3% |
| 45 | 22.9% | 16.4% |
| 50 | 25.2% | 18.9% |
| 55 | 26.3% | 20.9% |
Measuring Body Fat Percentage
U.S. Navy Method:
Body fat can be measured in a number of different ways. The above calculator uses a method that Hodgdon and Beckett came up with at the Naval Health Research Center in 1984. This method uses equations. Here are the ways to measure the important body parts and the specific equations that are used:
- For men, measure the waist at a horizontal level around the navel, and for women, measure at the level with the narrowest width. To get accurate measurements, make sure the person doesn’t pull their stomach in. Start measuring the subject’s neck’s circumference below the larynx and slope the tape down toward the front. The person in question shouldn’t stick their neck out.
- Only for women: Measure the size of the person’s hips at their widest point horizontally. Once you have these numbers, you can use the following formulas to get a rough estimate of your body fat. One uses the U.S. customary system (USC), which measures in inches, and the other uses the International System of Units, which measures in centimeters:
Body fat percentage (BFP) formula for males:
| USC Units: |
| BFP = 86.010 log 10 (abdomen-neck) – 70.041 log 10 (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 an estimate since they are based on many different assumptions to make them as applicable to as many people as possible. For more accurate measurements of body fat, the use of instruments such as bioelectric impedance analysis or hydrostatic density testing is necessary.
There are several equations that can be used to estimate body fat percentage, including:
- Body Mass Index (BMI) Equation: BMI = weight (kg) / height^2 (m^2)
- Jackson-Pollock 3-Site Skinfold Equation: % body fat = (0.7285 x sum of 3 skinfold measurements) – 5.4
- Durnin-Womersley 4-Site Skinfold Equation: % body fat = (4.95 / sum of 4 skinfold measurements) – 4.5
- Bioelectrical Impedance Analysis Equation: % body fat = (1.2 x total body water) / weight – 5.4
- Hydrostatic Weighing Equation: % body fat = (495 / body density) – 450
These equations are just estimates and may not be accurate for everyone, especially for individuals who are highly muscular or have a different body composition. It’s always best to consult with a healthcare professional for a more accurate assessment of your body fat percentage and overall health.
Fat mass (FM) formula:
FM = BF Weight
Lean Mass (LM) Formula:
LM = Weight – FM
BMI Method:
The BMI is another way to figure out how much body fat a person has. Use the BMI Calculator to get an estimate of your BMI using the BMI method, as well as more information about how BMI is calculated, what it means, and where it falls short. In short, to figure out a person’s BMI, you use formulas that require you to measure their height and weight. The following formulas can be used to figure out a person’s body fat percentage based on their BMI.
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
What Are Overweight and Obesity?
Overweight and obesity are common in the United States. They are both caused by fat cells getting bigger and more of them. Overweight and obesity are caused by many things, such as the way people eat, how much sleep or exercise they get, the medicines they take, their genes, and their family history. Obesity is a long-term health problem that increases the risk of heart disease, which is the leading cause of death in the United States, and is linked to many other health problems, such as type 2 diabetes and cancer.
Nearly three out of every four adults in the United States who are 20 years old or older are either overweight or obese. Nearly 1 in 5 kids and teens between the ages of 2 and 19 is overweight. People of all ages can have serious health problems because they are too fat or too heavy. Body mass index (BMI) is a way for adults to be checked for being overweight or obese. The body mass index (BMI) is a way to measure body fat based on height and weight. It is calculated by dividing the body weight (in kilograms) by the square of the body height (in meters).
If your BMI shows that your weight is too high for your height, your doctor may talk to you about being overweight or obese. But BMI is not the only measure of obesity. If you don’t get enough exercise and eat and drink things that are high in calories but low in nutrients, you may be more likely to be overweight or obese. Some people gain weight when they start taking medicine for something else, like diabetes, depression, or high blood pressure. Talk to your doctor before you decide to stop taking a medicine for something else that you think may also be affecting your weight.
Changes to your lifestyle that can help you lose weight include eating a heart-healthy diet that is low in calories and unhealthy saturated fats and getting more exercise. The Food and Drug Administration (FDA) has also approved medicines and other treatments for weight loss. Surgery is another possible treatment, but not everyone can get it.
Body Fat Calcalator Using Python
def body_fat_calculator(weight, height, age, gender):
if gender.lower() == 'male':
# Male formula
body_fat_percentage = (1.20 * float(weight) / float(height)**2) + (0.23 * int(age)) - 16.2
elif gender.lower() == 'female':
# Female formula
body_fat_percentage = (1.20 * float(weight) / float(height)**2) + (0.23 * int(age)) - 5.4
else:
# Invalid gender
return "Please enter a valid gender ('male' or 'female')"
return round(body_fat_percentage, 2)
# Example usage
weight = input("Enter your weight in pounds: ")
height = input("Enter your height in inches: ")
age = input("Enter your age in years: ")
gender = input("Enter your gender (male/female): ")
body_fat_percentage = body_fat_calculator(weight, height, age, gender)
if isinstance(body_fat_percentage, float):
print("Your estimated body fat percentage is: ", body_fat_percentage)
else:
print(body_fat_percentage)
In this example, the body_fat_calculator function takes in the user’s weight, height, age, and gender as arguments and returns an estimated body fat percentage based on their gender. The formula used for the calculation is based on the Jackson & Pollock 3-site skinfold test, which is one of the most commonly used methods for estimating body fat percentage.
Note that this is just a simple example and there are many different formulas and methods that can be used to calculate body fat percentage. Additionally, the accuracy of the results can be affected by various factors such as hydration levels, muscle mass, and body type. It’s always best to consult with a healthcare professional for a more accurate assessment of your body fat percentage and overall health.