Your body fat percentage is the ratio of fat to everything else in your body (actually everything – muscles, bones, organs, tendons, water…everything). Calculating this ratio is a hassle. Luckily, wikiHow can help you calculate your body fat percentage using intake and output.
Calculate Body Fat Percentage at Home
Determine your body mass index (BMI). Body mass index is calculated based on your weight and height. The easiest way to calculate your BMI is to use an online calculator. All you have to do is type “calculate body mass index” into your favorite search engine. You will be asked to enter your weight and height into the calculator.
- If you’d rather do the calculations yourself, that’s okay! If you are using the metric system, the formula is weight in kilograms divided by height squared. For example, if your height is 175 cm (1.75 m) and your weight is 78 kg, your BMI is 25.5.
Use your BMI to find your body fat percentage. The equation is (1.20 x BMI) + (0.23 x age) – (10.8 x gender) – 5.4. If you are male, your gender number is 1. If you are female, your gender number is 0.
- For example, if your BMI is 25.5 and you are a 30-year-old male, your formula would be (1.2 x 25.5) + (.23 x 30) – (10.8 x 1) -5.4. This would equal 30.6 + 6.9 – 10.8 – 5.4 = 21.3.
Measure your bioelectrical impedance. Fat tissue cannot conduct electricity. When you measure your bioelectrical impedance, you are testing the amount of fat tissue relative to other tissues in your body. This method does not require specialized personnel and the equipment is not very expensive. You have to stand barefoot on a metal plate that sends an electric current through your body. When the equipment works normally and the person being measured follows certain rules, the bioelectrical impedance obtained has only an error of 3%. Instruments that can measure bioelectrical impedance can be used at home and can be purchased online or in fitness stores.
- This method requires no food or water for 4 hours beforehand, no exercise for 12 hours, no alcohol for 48 hours, no diuretics, and a complete urinary tract.
- This approach can be used at health clubs, health fairs and schools, often for free or at a low cost.
Measure yourself with a tape measure. This isn’t the most accurate method, but it can give you an estimate of your body fat percentage. The most traditional way to use a tape measure to calculate fat percentage is the U.S. Navy method. See “How to Measure Body Fat Using the U.S. Navy Method.”
Use a caliper to check your body fat percentage. This method involves pulling your fat away from your muscle tissue and squeezing it with calipers. Then take measurements and compare based on the provided chart. This test has a 3% error if the test is administered correctly. For very thin or very fat people, the measurement error is larger. The test is suitable for use in schools, health clubs, recreational programs, hospitals, and laboratories. It’s cheap and often free.
Calculate Body Fat Percentage with Instrument
Underwater weighing machine. Underwater weighing is the most accurate way to determine body fat percentage and calculate how much water your body produces. If the test is carried out according to the guidelines, the error is 1.5%. To find this facility near you, use your favorite search engine and search for “underwater weighing machines near [your city].”
- Remember, the person being measured must be able to push all the air out of their lungs. This is only available in research institutions and specialized facilities, and if you are not involved in a study at the factory, it is expensive to do.
Measured with an infrared analyzer (IRI). This method measures body composition by using a fiber optic probe (or light absorption tool) to measure the composition (fat and water levels) of various parts of your body. It has an error of greater than 4%, however, the inaccuracy is higher in leaner and obese people. It may be available in some health clubs and weight loss centers for a lower fee.
Use the Bod Pod facility. Bod Pod measures body composition through air displacement. This method has an error of 3%. It is only available in a few research laboratories and professional athletic facilities. It is an excellent way to measure the body composition of children, the elderly, obese and disabled people.
Use a device with a dual-energy X-ray absorptiometry (DEXA) scanner. DEXA is a very accurate method of determining body composition. It uses a combination of two X-rays to calculate body composition. It is only available at scientific research facilities, but is generally free for use by those involved in research.