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.
Underweight: BMI below the 5th percentile
Normal Weight: BMI at the 5th percentile and less than the 85th percentile
Overweight:BMI at the 85th percentile and below the 95th percentile
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.
