For children and teenagers, BMI is interpreted differently compared to adults because it needs to account for age and sex. This measurement is often referred to as BMI-for-age. Child Body Mass Index Calculator (BMI) is a quick tool that healthcare providers use to assess a child’s risk for certain health conditions.

BMI Calculator

Use this calculator to check your kid's body mass index (BMI).

Unit type Metric Imperial

Select gender

Boy Girl

Age

yr.

mth.

Please enter value between 0 and 19 years.

Height

cm.

Please enter value between 40 and 225.

Weight

kg.

Please enter value between 1.0 and 250.0 ( one decimal ).

Height

ft.

in.

Please enter value between 1.4 and 7.3

Weight

lb.

st.

Please enter value between 2.3 and 500.0 ( one decimal ).

Calculate BMI

Use this calculator to check your body mass index (BMI), which can be a helpful tool in determining your weight category. Or, use it to calculate your child’s BMI.

Based on your inputs your child's BMI is:

Your child's BMI for age is placed in the greater than XPERCENTILE percentile for a XYEAR year and XMONTH month XGENDER.

1

99

This falls in the XCATEGORY BMI category.

A healthy weight for your childs age and height is between XMINMAX kg

A healthy weight for your childs age and height is between XMINMAX lb

Age and Sex Distribution

After the BMI is calculated, it is plotted on the CDC BMI-for-age growth charts (for boys or girls) to obtain a percentile ranking.
This percentile indicates the relative position of the child’s BMI number among children of the same sex and age.

BMI-for-age Categories

Based on CDC guidelines, here’s what the BMI ranges mean for children:

• Underweight: In the bottom 5% of kids the same age and sex
• Healthy Weight: Between the bottom 5% and top 15% of kids the same age and sex
• Overweight: Between the top 15% and top 5% of kids the same age and sex
• Obese: In the top 5% of kids the same age and sex.

These categories help understand if a child’s weight is within a healthy range compared to other children of the same age and sex

Implications of Child BMI calculation

Health Monitoring:
BMI-for-age is a useful tool to screen for potential weight-related health issues. However, it is not diagnostic. Further evaluations are often needed to determine body fat and health status more accurately.

Growth and Development:
Child BMI helps track growth patterns and development over time, ensuring children are growing as expected and identifying any early signs of health issues.

Nutritional and Lifestyle Intervention:
Identifying children who are underweight, overweight, or obese early can help implement appropriate nutritional and lifestyle interventions. This includes making dietary changes, increasing physical activity, and addressing any underlying health conditions.

Limitations

Like adult BMI, BMI-for-age has limitations. It does not directly measure body fat and can be influenced by muscle development, especially in children who are particularly athletic. Healthcare professionals often use it as a starting point, conducting further assessments if necessary.

If you would like to know the BMI for adults please see our Adult BMI Calculator.