The Normal Weight for 13 Year Olds

Defining a normal weight range for a 13 year old can be tricky. Several factors affect a person's weight regardless of her age, such as gender, genetics and underlying health issues 3. A young teen will need to use several tools, including the bathroom scale and a body mass index (BMI) reading, to determine whether his weight is within a range that is considered to be normal 2.

Height to Weight Ratio

A standard chart used by paediatricians says a 13-year-old boy should weigh between 38.6 and 45.4 Kilogram and a 13-year-old girl should be between 43.1 and 45.4 Kilogram. These weight recommendations are based on assumptions that the average height for a boy is 58 to 62 inches, and the average for a girl is 60 to 63 inches. These figures should be regarded as estimates because they do not take into account a young person's previous growth patterns and actual height. Some 13 year olds are well into puberty, whereas others are just starting their adolescent growth spurt.

Figuring Out BMI

The BMI is a calculation that determines a person's percentage of body fat based upon both height and weight. Centers for Disease Control and Prevention (CDC) provides an online calculator that allows anyone to type in their gender, height and weight and see their BMI percentage. Separate versions are available for children and teens as well as adults. For example, a 13-year-old boy who weighs 59 Kilogram and stands 5 feet 6 inches tall would have a BMI of 21 per cent, which is considered to be within a normal range. A high BMI means a high concentration of body fat. Healthy readings for both adults and youngsters are between 18.5 and 24.9 per cent.

Family Influence

Genetics and family lifestyles are key contributors to a teenager's weight. Some ethnic groups have specific distributions of body fat, meaning they carry their weight in different parts of their bodies in response to their places of origin. That heritage can have bearing on a person's weight blueprint generations later. Also, a 13 year old's eating habits often are passed on to him by his parents, so that a youngster with a healthy BMI may be eating lots of fresh produce and other wholesome foods. The same teenager is likely to engage in outdoor activities, while another 13 year old may evidence a higher BMI because her family consumes high-calorie snacks and seldom exercises.


For many reasons, parents should consult a paediatrician when determining whether a 13-year-old son or daughter is at a normal weight. It is typical for adolescent girls, for example, to experience fluctuations in their weight and BMIs. But the doctor and parents need to ensure that such swings are not symptoms of a more serious underlying condition, such as diabetes or an eating disorder. Weight charts and body mass indexes serve as overall guidelines, but paediatricians can provide insight into the specific factors that may be affecting your teenager's development.

Healthy Habits

As useful as the BMI and the paediatrician's input are, parents and young teens need to look past the numbers. In order to maintain a normal body weight, it's important to develop healthy eating habits and stay physically active.