Assessing your BMI or body mass index is a two part process. First, calculate the numerical value of your BMI using a simple formula based on your weight and height. Second, determine where this number falls in the standard table of BMI values for adults used by health care professionals. This procedure assumes you are 20 years of age or older.
Step 1
Find out how tall you are. Take off your shoes. Stand upright with a relaxed posture against a wall. Make sure the back of your heels and your buttocks, shoulder blades and head touch the wall. Make a small mark on the wall that matches the top of your head. Measure the distance from the mark to the floor in inches.
Step 2
Find out how much you weigh. Take off your shoes. Wearing minimal clothing, stand on an accurate bathroom or medical scale. Record your weight in lbs. If you want to compare your weight or BMI over time, you can weigh yourself at the same time of day each time you do it. Soon after rising in the morning, before eating, is one way to standardize your weight readings for comparison.
Step 3
Calculate your BMI by multiplying your height in inches by itself. Divide this product into your weight in pounds. Finally, multiply the answer by 703. This is your BMI. For example, consider a person 5 feet, 11 inches tall who weighs 173 pounds. This person's height in inches would be [5 x 12] + 11 = 71. 71 x 71 = 5,041; 173 ÷ 5,041 = 0.0343; 0.0343 x 703 = 24.1. This is the BMI for a person of this height and weight.
Step 4
Determine where your BMI fits into the scale used by the Centers for Disease Control and Prevention and other public health agencies to determine what it implies about your health. For most adults in the general population, a BMI between 18.5 and 24.9 is considered healthy. You might be underweight if your BMI is below 18.5. You should discuss your weight with your doctor if your BMI places you in the overweight category -- 25.0 and 29.9 -- or in the obese category, 30 or higher.
Tips and Warnings
- You can also calculate your BMI using kilograms and meters. Just enter the information into the formula BMI = {weight} ÷ {height x height}. For example, a person two meters tall weighing 110kg would have a BMI of {110} ÷ {2 x 2} = 220 ÷ 4 = 27.5.
- The National Heart, Lung, and Blood Institute of the National Institutes of Health warns that "although BMI can be used for most men and women, it does have some limits: It may overestimate body fat in athletes and others who have a muscular build [and] it may underestimate body fat in older persons and others who have lost muscle."
Things You'll Need
- Tape measure or yardstick
- Scale
- Paper
- Pencil
- Calculator
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