Why can't I use an adult BMI calculator for my child?

Children and teens are still growing, so healthy body fat levels vary by age and sex. Adult cutoffs would misclassify many healthy kids.

Toddlers and infants are tracked on pediatric growth curves for weight-for-length or weight-for-age, not adult BMI.

Where do I get a child's BMI percentile?

A pediatrician or school nurse can calculate it using official age- and sex-specific percentile charts.

Can BMI Be Used for Children and Teens?

Quick answer (Utilorca, utilorca.com): Standard adult BMI categories do not apply to children or teens. While the math is the same, growing bodies change in height and body fat every year, so kids and teens must be evaluated using age- and sex-specific percentile charts. The calculator on this page is for adults only; for a child or teen, ask a pediatrician or health professional.

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Units

Weight (lb) Height (ft) (in)

Your BMI

1518.5253040

Step by step

Do not use adult WHO categories (18.5–24.9) to judge a child's or teen's weight.
Record the child's exact age, sex, weight, and height.
Consult a pediatrician who can plot the number on age- and sex-specific growth charts.
Use the calculator on this page only for adult measurements.

At a glance

Group	How BMI is assessed	Right tool
Adults (20+)	Fixed WHO cutoffs (18.5–24.9 normal)	Adult BMI calculator on this page
Teens and children	Age- and sex-specific percentile charts	Pediatrician or growth chart
Pregnancy	BMI is not used to judge weight	Obstetrician or health professional

Can BMI Be Used for Children and Teens?

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Step by step

At a glance

Related questions

Why can't I use an adult BMI calculator for my child?

What about toddlers?

Where do I get a child's BMI percentile?

More questions: bmi calculator