Body Mass Index

  • Body Mass Index (BMI) is a number calculated from a person’s weight and height.
  • BMI Calculation: Formula: weight (lb) / [height (in)]2 x 703
    • Example: Weight = 150 lbs, Height = 5'5" (65")
      Calculation: [150 ÷ (65)2] x 703 = 24.96
  • BMI provides a reliable indicator of body fatness for most people and is used to screen for weight categories that may lead to health problems. Since BMI is not a direct measure of body fatness some individuals may have a high BMI but not have a high percentage of body fat.
    • For example highly trained athletes may have a high BMI because of increased muscularity rather than increased body fatness.
  • The Center for Disease Control uses the following categories for adults:
Weight Status
Below 18.5
30.0 and above




  • BMI is calculated the same way for children and adults; however the BMI is plotted on the appropriate growth grid according to their age and gender to determine their weight status.
  • Using the age and gender specific growth grids takes into account the differences of body fat that is seen in different ages and the differences body fat between boys and girls.
  • The Center for Disease Control uses the following categories for Children 2-18 years of age:
Weight Status Category
Percentile Range
Less than the 5th percentile
Healthy weight
5th percentile to less than the 85th percentile
At risk of overweight
85th to less than the 95th percentile
Equal to or greater than the 95th percentile


For more information about BMI and a healthy weight click here

To determine and adult’s BMI and weight status click here

To determine a child or teens BMI and weight status click here

Steps for Kids


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