Children body mass index (BMI) is calculated differently than adults BMI calculation is done. Because kids’ body fat changes with age and because girls and boys differ in amount of body fat as they mature that’s why BMI calculation for children includes gender and age.

Child’s body mass index is compared with the average of other children by corresponding BMI-for-age (or Index-for-age) percentiles.

**This BMI calculator is for 5-19 age boys only.** Also check our Girls BMI calculator and Adults BMI calculator.

Calculator shows into which percentile range boys fall according to their age, weight and height:

Percentile is a measure in which the percentage value of the total values is equal to or less than this measure. For example, 90% of data values are below the 90th percentile, and 10% of data values are below the 10th percentile.

On a standard BMI chart, children aged 2 to 19 fall into one of four categories:

Less than 5th percentile – **Underweight**

5th percentile to less than the 85th percentile – ** Normal or Healthy Weight**

Between 85th and 95th percentiles – **Overweight**

Above 95th percentile – **Obese**

We are using BMI-for-age percentile based on the WHO (World Health Organization) growth charts for children and teens (ages 5 through 19 years). WHO Growth charts are slightly different from CDC ( Centers for Disease Control and Prevention) Grow charts. CDC charts describe the growth of children in the United States only while WHO Growth charts were designed to be an international standard for infants and young children.

For adults 20 years old and older, use the Adult BMI Calculator.

Use girls body mass index calculator for 5-19 years old girls.

For children under 2 years old, doctors use weight-to-length charts instead of BMI to determine how a child’s weight relates to his or her length. Any child under the age of 2 who falls into the mark up to the 95th percentile or higher can be considered overweight.