Child safety seats have requirements for both weight and height. The weight requirements of children are considered more important than the height requirements when using a car seat or booster seat.
Average Height Requirements
Car seat laws are determined by state, and the height varies between 36 inches to 57 inches. Car seats' restrictions are based primarily upon weight. Booster seats allow more restrictions based upon height, and the majority of states require that a child should be at least 57 inches before they stop riding in a booster seat.
Weight Versus Height
Weight is generally the measurement preferred for the restrictions on automotive car seats. It is preferred because the correlation between height and weight is not dependent upon one another. It is more likely for a child to reach a height requirement before they reach their weight requirements.
Height and weight are not the only restrictions for safety seats. Age is often a restriction, as well, and the average age for children to stop riding in car seats or booster seats is 8 years old.