Body Mass Index or BMI is a measure that, for adults and children, allows you to define if your weight is within the limits of what is considered healthy. Its a value obtained by dividing the weight in kilograms between the square of the height in meters. Its a very rough indicator of health, which serves only to identify people who may have a problem or who are at risk of health problems due to their weight.
The Centers for Disease Control and Prevention created BMI-for-age growth charts for both boys and girls to allow healthcare providers to see how a childs growth compares to others of their age and sex. These growth charts are used to assess whether a childs growth is on track and to determine if they are at risk for being overweight or obese.