BMI Calculator

BMI Chart
Ages 2-19
Under Weight < 18.5 < 5th
Normal Weight 18.5 to < 25 5th to < 85th
Overweight 25 to < 30 85th to < 95th
Obese (Class I) 30 to < 35 >= 95th
Obese (Class II) 35 to < 40 -
Obese (Class III+) >= 40 -

Health professionals use a BMI Calculator to determine if you are at a healthy weight for your age and height. You can enter some basic information about yourself into Pennington Biomedical’s BMI Calculator to learn the following:


BMI (Body Mass Index) is an estimate of body fat and is calculated for both children and adults. A high BMI might mean you are at a higher risk for diseases associated with obesity.

BMI Percentile

The BMI Percentile is calculated for children and young adults aged 2 to 19.  Health professionals can use the percentile score to categorize a child’s BMI to identify where the child falls in relation to other children of the same age and sex.


BMI Z-Scores are also calculated for children and young adults aged 2 to 19. This number indicates how much higher or lower your BMI is on a standard growth chart. BMI Z-Scores help health professionals to monitor weight changes in children and adolescents especially if they are in the underweight or overweight percentiles.