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BMI Calculator for Children

An easy way to measure BMI, for a child between 2 and 20 years old, is to use this calculator. Once you know your child's BMI it can be plotted on this chart.

Age years months
Height ft in
Weight lbs  

  1. Underweight: BMI below the 5th percentile
  2. Normal Weight: BMI at the 5th percentile and less than the 85th percentile
  3. Overweight:BMI at the 85th percentile and below the 95th percentile
  4. Obese:BMI at or above the 95th percentile
BMI is not a perfect measure of body fat and can be misleading in some situations. For example, a muscular person may have a high BMI without being overweight (because the extra muscle adds to the body weight - but not fatness). In addition, BMI may be difficult to interpret during puberty when kids are experiencing periods of rapid growth. It's important to remember that BMI is usually a good indicator - but nor a direct measure - of body fat.