Child & Teen BMI Percentile Calculator (CDC)
Calculate your child or teenager's BMI and see their exact BMI-for-age percentile using official CDC growth charts. For ages 2 to 20.
BMI-for-age percentiles differ for boys and girls.
Whole years. This tool covers ages 2 to 20.
Optional: extra months beyond whole years, for a more precise percentile.
Choose your measurement system.
Your child's weight (kg if metric, lb if imperial).
Your child's height (cm if metric, inches if imperial).
What a child BMI percentile means
For children and teenagers aged 2 to 20, BMI is not interpreted using the fixed adult categories. Because children are still growing and body composition changes with age and differs between boys and girls, a child's BMI is compared against other children of the same age and sex, and expressed as a percentile. For example, a child at the 60th percentile has a BMI higher than 60% of children the same age and sex. This calculator uses the official CDC BMI-for-age growth chart data to give an accurate percentile.
How the weight categories work
The CDC defines weight status for children and teens by BMI-for-age percentile: below the 5th percentile is underweight; from the 5th to below the 85th is a healthy weight; from the 85th to below the 95th is overweight; and at or above the 95th percentile is obese. These bands are screening categories, not diagnoses. A result near a boundary, or any concern, is best discussed with a pediatrician, who interprets it alongside your child's overall growth pattern, build and health rather than a single number.
Why growth over time matters most
A single BMI percentile is a snapshot. What tells a healthcare professional the most is how a child tracks along their own growth curve over time. Children generally follow a broadly consistent percentile band as they grow, and it is the trend, rather than one reading, that best shows healthy development. A sudden or sustained shift across percentile bands is the kind of thing worth discussing with a pediatrician, whereas steady tracking along a healthy curve is usually reassuring. Use this tool as a helpful screening guide alongside regular check-ups.
Frequently Asked Questions
Enter your child's sex, age (in years, plus optional months), weight and height, and choose metric or imperial units. The calculator works out their BMI and then compares it against CDC BMI-for-age growth chart data for their exact age and sex, giving a percentile and weight category. It works for children and teenagers aged 2 to 20.
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Sources & References
- 1.Centers for Disease Control and Prevention (CDC). BMI-for-age growth charts and percentile data.
- 2.CDC. About Child & Teen BMI.
- 3.World Health Organization. Child growth standards.
LifeCheckIQ content is based on peer-reviewed research, recognised clinical guidelines, and authoritative medical sources, and is reviewed by Deborah Adotso, General Nurse, for clinical accuracy.
Medical Disclaimer: This tool is for informational and educational purposes only. Results are not a medical diagnosis. Always consult a qualified healthcare professional for medical advice, diagnosis, or treatment. In an emergency, call your local emergency number or visit the nearest hospital immediately.