Charts for age, height and weight are used to provide a rough reference to determine how a child or teenager is developing, specifically whether he is underweight or overweight. Height/weight charts can be found online, or a doctor can consult one to provide a professional opinion.
At a given age, children should be within a certain height range. Falling too far outside this range can indicate a possible growth disorder related to the pituitary gland. It can also indicate malnourishment if the child is too far below proper height or weight.
Development is most crucial during the early formative years, so doctors watch more carefully during this time. As the child ages, the standard age-height chart gives way to BMI measurements. BMI, or Body Mass Index, is a calculation involving the ratio of weight to height. It is different for males and females.
Comparing height with weight on the chart indicates whether the child is within the proper weight range. However, different body types should be taken into consideration, as well as body composition, which is why BMI calculation is only a guideline for gauging health. Muscle weighs more than fat, but excess fat carries more risk of long-term health issues.