Your body fat percentage can reveal a lot about your health and potential health risks, but calculating body-fat percentage can be complicated. Some methods involve special or expensive equipment to measure the percentage of fat versus lean mass in your body. Other calculators, like the Body Mass Index (BMI), involve a few simple measurements but may not always be accurate. But with the variety of methods available, you may be able to compare the results of several methods to gain a more accurate understanding of your body composition.
Things You'll Need
- Measuring tape
- Body fat scale
Calculate Your BMI
Determine your Body Mass Index, or BMI. The BMI test does not directly measure body fat, but the number correlates with your body fat percentage. The BMI is the simplest and most cost-effective body-fat calculator to perform at home. All you need to know is your height and weight. You can record these measurements with a scale and a tape measure.
Calculate your BMI. You can plug these numbers into a reliable online calculator, such as the one on the Center for Disease Control's website, or you can calculate your BMI manually using the following formula:
Your weight (lb) / [Your height (in)]^2 x 703
Interpret your results. In general, a BMI between 18.5 and 24.9 is considered within the healthy weight range. A BMI of 25 and above is considered overweight. However, BMI does not take age, gender or physical fitness into account. At the same BMI, women tend to have more body fat than men, and older adults tend to have more body fat than younger adults. Athletes may also have a high BMI due to a high percentage of muscle mass rather than body fat.
The Skinfold Test
Measure skin-folds on certain areas of your body using calipers. Personal trainers favor this method of body fat calculation and it is more accurate than many other methods with a 3.5% margin of error. It may be helpful to have someone else, such as a personal trainer or physician, take the measurements.
Identify each site that needs to be measured on the body. For men, the significant measurements should be taken at the chest, midway up the thigh and at the naval. For women, measurements should be taken halfway up the triceps, halfway up the thigh, and at the crest of the ilium, one of the pelvic bones. For each site, identify the location of the skin-fold, and record all measurements on the right side of the body.
Grasp the skin-fold with the thumb and index finger of the left hand. Place the pads of the calipers perpendicular to the site, approximately 1/4-inch from the thumb and forefinger. Wait one or two seconds after the trigger is released, then read the dial to the nearest 0.5 mm.
Take further measurements at each site. Each site should be measured at least twice, until two measurements vary by at least 1 mm.
Interpret your results. If you are working with a professional to measure your body fat percentage, he or she will help you to do this. If you are on your own, the simplest way to interpret the results is to enter your measurements into an online calculator, such as the one at the American Council on Exercise's website.