One of the biggest questions guys and girls have as they grow and develop is whether they're the right weight. One place to start is by learning about body mass index, or BMI, a calculation that estimates how much body fat a person has based on his or her weight and height.

BMI can help doctors identify people who are overweight and at risk of developing medical problems like high cholesterol, high blood pressure, and diabetes. Doctors can monitor that person's weight and make recommendations about healthy eating and exercise.

Our BMI calculator can help you find out what your BMI is. When you get your results, it's a good idea to ask a doctor or health professional to help you figure out what they mean. That's because BMI is not perfect. For example, it's very common for teens to gain weight quickly — and see their BMI go up — during puberty. Those changes may be a normal part of development (for example, someone with a large frame or lots of muscle can have a high BMI.) Or, the changes can be a sign of future weight problems.

Your doctor can help you figure out whether weight gain is a normal part of development or whether it's something to be concerned about.

Reviewed by: Mary l. Gavin, MD
Date reviewed: March 2011