How to Calculate Your BMI With Age

The National Heart Lung and Blood Institute provides a body mass index chart and guidelines for understanding your index. Body mass index, abbreviated as BMI, refers to body weight relative to height. Age and height help to determine a normal body weight for a child or adolescent. BMI calculators with a feature that includes adult age ranges show how your body mass compares with the average American body mass for your height and age. The Mayo Clinic's online BMI calculator offers results for adults or children.

Instructions

1

Navigate your browser to a BMI calculator that offers results related to age (see Resources section).

2

Enter your weight. Specify pounds or kilograms.

3

Enter your height, and specify inches or centimeters (cm).

4

Enter your age. Enter your gender.

5

Click "Calculate."

6

Double-check your results by re-entering all the numbers to make sure the results are accurate.

7

Refer to the website's information about your results. For example, a BMI of 18.5 to 24.9 is normal, for example, according to the National Heart Lung and Blood Institute. A BMI under 18.5 signifies underweight, and a BMI over 24.9 signifies overweight. A BMI over 29.9 indicates obesity. Weight ranges related to age are offered on Dr. Hall M.D.'s website (see Resources section).