The National Highway Traffic Safety Administration (NHTSA) provides guidelines on its website for child safety seat usage (see link in Resources). Here are the guidelines for when and why to use a booster seat, as well as a few safety tips.
At age 4, children should move to a booster seat if their height and weight are appropriate.
Children should be 36 inches tall.
Children should weigh 40 pounds.
Seat belts are designed for adults, so a booster seat is needed to raise the child to a level where he can be safely and effectively restrained by the belt.
Booster seats should always be secured in the back seat, and the shoulder belt should be positioned in front of the child's body and not under his arm.
