How to Calculate Body Mass Index

Even though most people still use a bathroom scale to determine whether or not they are overweight, body mass index is a better indicator. A person's body mass index estimates the total body fat of a person, and displays it in the form of a number that shows whether he is underweight, normal, overweight or obese. The best part about a body mass index is that it's very easy to calculate.

Instructions

• 1

  Get an accurate reading of your weight on a scale. While any scale is acceptable for this, a digital scale will provide the most accurate reading. If you are using a bathroom scale, make sure it has been properly calibrated.

• 2

  Measure your height. To get the best result, stand up straight against a wall, then make a mark with a pencil along the top of your head. Use a tape measure instead of a ruler or yardstick to avoid inaccuracies.

• 3

  Multiply your height by itself to get its square number. Use inches if you live in the United States, or meters if you live in a country that uses the metric system.

• 4

  Divide your weight by the square number of your height. Your weight should be recorded in pounds if you live in the United States, or in kilograms for countries that use the metric system.

• 5

  Multiply the result by 703 if you recorded your weight and height in pounds and inches. The resulting number is your calculated body mass index.

• 6

  Do nothing with the result if you live in a country that uses the metric system. The result itself is your calculated body mass index.

• 7

  Compare your results to a body mass index chart such as the one at Healthy Weight Management to calculate what your status is (see Resources below). In general, a result between 18.5 and 25 is optimal, while a number significantly higher or lower is cause for concern.