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Your Family

Know your child's Body Mass Index (BMI)

Take This Action Commit to this action for your family to help overcome the obesity epidemic.

BMI is calculated using a child's weight and height and, although it does not measure body fat directly, it is a good indicator of body fatness for most children and teens.

To determine your child's weight status, you must use age- and sex-specific percentiles for BMI rather than the BMI numbers used for adults, because children's bodies change as they age and are different between boys and girls.

Gathering Information

To use the BMI calculator for children you need to gather some information - your child's height, weight, date of measurement, date of birth, and sex.

Guidance on how to measure your child using a BMI calculator. The calculator results will explain which weight category your child is in.

For children, BMI is used to screen for obesity, overweight, healthy weight, or underweight. However, BMI is not a diagnostic tool. For example, a child may have a high BMI for age and sex, but to determine if excess fat is a problem a health care provider would need to perform further assessments. These assessments might include skinfold thickness measurements and evaluations of diet, physical activity, family history, and other appropriate health screenings.

BMI-for-age weight status categories and the corresponding percentiles are shown in the following table.

Weight Status Category

Percentile Range


Less than the 5th percentile

Healthy weight

5th percentile to less than the 85th percentile


85th to less than the 95th percentile


Equal to or greater than the 95th percentile

Read the Disclaimer

The information included on this site is for educational purposes only. It is not intended nor implied to be a substitute for professional medical advice.


Overweight and obese children are at risk for serious health problems including high blood pressure, orthopedic problems, type 2 diabetes, breathing problems, and social and psychological problems.