A medical weight chart, also known as a body mass index (BMI) chart, provides a list of heights and weights that indicate the BMI for each height and weight combination. A BMI number indicates if patients are at a healthy weight, explains the Centers for Disease Control and Prevention (CDC).
BMI is used to determine the weight category that a patient is in, such as underweight, normal, overweight and obese. BMI is a number derived from a mathematical formula that takes a person's height in meters and divides it by the square of the person's weight in kilograms. The resulting BMI falls within a range of numbers that defines various weight categories. For a person to be at a healthy weight, as stated by the CDC, the BMI should fall between 18.5 and 24.9, while a BMI below 18.5 is considered underweight. A BMI between 25 and 29.9 is categorized as overweight, and a BMI of 30 or higher indicates that a person is obese.
For children and teens, BMI is interpreted differently, but it is calculated using the same formula used for adults. The BMI of children and teens varies with age and sex because the percentage of body fat changes with age, and the amount of body fat differs between girls and boys, according to the CDC.