BMI Calculator for Teens

BMI Calculator for Teens. Enter your teen's gender, age, height, and weight to calculate their BMI (Body Mass Index) and see where they fall on the CDC age-specific growth percentile for teens ages 10–20. You get back the BMI value, percentile ranking, and a weight category (Underweight, Healthy Weight, Overweight, or Obese) tailored to their age and gender. Also try the Body Frame Size Calculator.

Results

BMI Value

BMI Percentile

Weight Category

Healthy BMI Range for Age & Gender

What is BMI and why does it matter for teens?

BMI (Body Mass Index) is a number calculated from a person's height and weight that estimates body fat levels. For teens, it matters because excess or insufficient body fat can affect long-term health, development, and well-being. Doctors use BMI-for-age charts to track growth patterns over time and identify potential weight-related concerns early. See also our BMI Calculator for Women.

Why does teen BMI use age and gender instead of just height and weight?

Unlike adult BMI, teen BMI-for-age accounts for the fact that body fat naturally changes as children grow, and boys and girls differ in body fat composition during puberty. By comparing a teen's BMI to others of the same age and gender on a CDC growth chart, the result is much more meaningful and accurate than a single cutoff number.

What do the BMI percentile categories mean for teenagers?

Teens are grouped into four categories based on their BMI percentile: Underweight (below the 5th percentile), Healthy Weight (5th to less than 85th percentile), Overweight (85th to less than 95th percentile), and Obese (95th percentile or above). These ranges are set by the CDC and are specific to age and gender.

Can a teen have a high BMI but still be healthy?

Yes. BMI is not a direct measure of body fat. Teens with a large frame or significant muscle mass may have a higher BMI without excess fat. Conversely, a teen with a normal BMI could still carry too much body fat if they have low muscle mass. BMI is a useful screening tool, but a healthcare provider should evaluate the full picture.

Is it normal for a teen's BMI to change during puberty?

Absolutely. It is very common for teens to gain weight quickly and see their BMI rise during puberty as part of normal development. This is one reason why BMI is tracked over multiple visits rather than assessed at a single point in time. A doctor can help determine whether any change is expected or worth monitoring further.

What should I do if my teen's BMI is in the overweight or obese range?

The first step is to speak with your teen's doctor or pediatrician rather than making drastic dietary changes on your own. A healthcare provider can assess whether the BMI reflects actual excess fat and recommend appropriate steps, which may include dietary adjustments, increased physical activity, or further evaluation. Avoid placing excessive focus on weight with teens, as this can negatively affect mental health.

How accurate is this BMI calculator for teens?

This calculator uses the standard BMI formula and CDC-based age-and-gender percentile approximations to give a reliable estimate. However, it does not account for muscle mass, bone density, ethnic background, or physical activity levels. The results are intended for informational purposes and should be discussed with a healthcare professional for a complete assessment.

What is a healthy BMI range for a 15-year-old?

Healthy BMI ranges vary by age and gender. For a 15-year-old boy, a healthy BMI is typically between about 17.0 and 23.4, while for a 15-year-old girl it is roughly 17.2 to 24.4. These ranges are based on the 5th to 85th percentile of the CDC growth charts. This calculator will show you the specific healthy range for your teen's age and gender. You might also find our Army Body Fat Calculator useful.