Body mass index (BMI) is a measure used by health care professionals to determine if a person is of normal weight, based on height. The BMI number corresponds to different categories: underweight, normal weight, overweight or obese. These categories are somewhat associated with expected body fatness and risks for chronic diseases. Calculating your own BMI provides some insight into how healthy your weight is, but a health care practitioner should ultimately be the one to interpret the results and their implications.
Step 1
Weigh yourself on a reliable scale and record your weight. An ideal time to this is first thing in the morning before you have eaten, and after you have used the bathroom.
Step 2
Stand erect against a wall with your weight evenly distributed on both feet. Have someone measure and record your exact height with a tape measure.
Step 3
Determine which formula to use to calculate your BMI based on whether you recorded your height and weight in pounds and inches or metric units. BMI is equal to weight in pounds divided by height in inches, squared, then the result of that is multiplied by 704.5. With metric units, BMI is equal to weight in kilograms divided by meters, squared. Use a calculator to determine your BMI and record the result.
Step 4
See how you are categorized based on your BMI. For adults, a BMI less than 18.5 is underweight; 18.5 to 24.9 is normal weight; 25 to 29.9 is overweight; and 30 or greater is obese.
Tips and Warnings
- When measuring your weight, remove any unnecessary clothing to prevent an inaccurate BMI calculation. When measuring your height, make sure shoes are removed and your assistant compresses your hair, if necessary, to get an accurate measurement. When calculating your BMI, your height must be squared. Your height squared would be your height times your height.
- BMI can be drastically inaccurate in some people, such as athletes, with above-average lean body mass, and elderly people who have lost lean body mass. Disparities also exist in actual fat mass at the same BMI for different age, gender, ethnicity, and race groups.
Things You'll Need
- Scale
- Tape measure
References
- "Sports & Exercise Nutrition, 2nd Ed.;" W.D. McArdle, F.I. Katch, V.L. Katch; 2005
- Weight-Control Information Network: Statistics Related to Overweight and Obesity
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