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Body Mass Index: Calculate Your Child's BMI
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Calculate Your Child's BMI

Calculate Your Child’s Body Mass Index (BMI)

2—20 Years of Age   

When calculating your child’s BMI, even a slight weight or height miscalculation can significantly skew BMI values and the resulting BMI Percentile. We recommend allowing a health care professional to assist you during this process. If you are under the age of 18, you must have your parent or guardian’s assistance. 

The following BMI Calculator and BMI Percentile Graphs are for determining the BMI Percentile of a child through young adult between the ages of 2 – 20 years.    

To determine your child’s BMI

  1. Enter your child’s height and weight into the BMI Calculator.
  2. Click calculate to compute your child’s BMI.
  3. Plot your child’s BMI on the following BMI Percentile Graph.

Body Mass Index Calculator

Child Body Mass Index (BMI) Percentile Graphs

Once you have determined your child's BMI, you must then use the following graphs to determine your child’s BMI Percentile.  There is one graph for boys and another graph for girls.    

To determine your child’s BMI Percentile

  1. Find your child’s age along the horizontal (across) axis and your child’s BMI along the vertical (up – down) axis. 
  2. Your child’s BMI Percentile will be between 5 – 95%, and is where the two points meet. 

BMI Chart - Boys

BMI Chart - Girls

BMI Percentile Ranges For Your Child; What They Mean

2 – 20 years of age

Your child’s BMI Percentile indicates how their height and weight compare to other boys and girls within their same age group.   An ideal weight for a child is between the 5th and 85th percentile. 

  • Underweight:  Less than the 5th percentile. It is important to have your child’s nutritional needs evaluated to ensure that he or she is achieving adequate nutrition for proper growth and development.
  • Ideal Weight: Between the 5th and 85th percentiles.  The 50th percentile is the average healthy weight for all children.
  • At Risk for being Overweight:  Between the 85th and 95th percentile.  Children within this percentile are at risk of being overweight as adults.  Identifying children in this percentile early on and preventing further weight gain is extremely important.  Close monitoring and implementation of a weight maintenance program including teaching healthy eating and exercise habits can help to prevent adult obesity.  
  • Overweight:  Above the 95th percentile.  Children within this percentile need intervention in the form of a weight loss and weight management program designed around your child’s individual needs and interests.  Intervention is necessary to prevent your child from remaining at an unhealthy weight through their developmental years and also to prevent adult obesity.