BMI is a calculation that uses a person's height and weight to estimate how much body fat he or she has. Doctors use BMI to determine how appropriate a person's weight is for a certain height and age.

Calculating BMI

The best way to determine your child's BMI is to have your child's doctor do it. That way, you'll know the number is accurate and your child's doctor can discuss the result with you. If you're interested, you also can figure out your BMI by using this calculator: