How to Compute Body Fat Percentage

by Laura Dattaro

Overview

Many people rely solely on the number of the scale to determine their health. But there are other factors that can indicate a person's need to gain or lose weight. The percentage of body fat gives a more complete picture of the composition of the body. Using this information, along with the Body Mass Index (BMI), which measures one's weight comparative with height, can help design one's diet and fitness needs more accurately than weight alone.
Exact Body Fat Percentage

Step 1

Measure the circumference of your neck and waist, in centimeters. If you are female, measure your hips. Men should measure their waist at the belly button, while women should measure around the narrowest portion of the midsection. Women should measure hips at their widest point.
Step 2

Stand up straight against a wall and make a light pencil mark at the top of your head. Measure the distance, in centimeters, from the floor to this mark, to obtain an accurate height measurement.
Step 3

Enter your measurements into the following formula: Men: Percent body fat = 495/(1.0324-0.19077(log(waist-neck))+0.15456(log(height)))-450 Women: Percent body fat = 495/(1.29579-0.35004(log(waist+hip-neck))+0.22100(log(height)))-450 According to the American Council on Exercise, an acceptable level of fat is 25 to 31 percent for women, and 18 to 25 percent for men. Anything higher is considered obese.

Body Mass Index (BMI)

Step 1

Weigh yourself on a scale. If measuring in kilograms, convert your height in centimeters to height in meters by diving by 100. If measuring your weight in pounds, find your height in inches.
Step 2

Enter your measurements into the following formula: BMI = (Weight in pounds X 703) / (height in inches ^2) or BMI = (Weight in kilograms) / (height in meters ^2)
Step 3

Compare your BMI to the following standards: Below 18.5 = underweight 18.5 to 24.9 = normal 25 to 29.9 = overweight 30 or over = obese

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Measuring tape with centimeter markings Calculator with log capabilities
Measuring tape with centimeter markings
Calculator with log capabilities
Bring your results to a physician or dietitian, if desired. They can better interpret the results and assess any possible risks. Keep in mind that a BMI measurement excludes many factors, such as age, gender and level of fitness. For example, because women naturally have more body fat than men, they tend to have higher BMI ratings, which is perfectly healthy.
Bring your results to a physician or dietitian, if desired. They can better interpret the results and assess any possible risks.
Keep in mind that a BMI measurement excludes many factors, such as age, gender and level of fitness. For example, because women naturally have more body fat than men, they tend to have higher BMI ratings, which is perfectly healthy.