Booster Seats

Once they're 4'9" tall, usually between ages 10 and 12.  That's the height where a vehicle seat belt sits correctly across the chest and hips without help. Many state laws allow kids to stop using a booster at age 8, but the AAP, NHTSA, and IIHS all recommend waiting until your child passes the seat belt fit test: back against the seat, knees bent over the edge, lap belt low on the hips, and shoulder belt across the chest rather than the neck. Legal minimums and best practice are usually a few years apart, so when in doubt, keep the booster.

Only switch if your child has outgrown the high-back. Many high-back boosters fit kids through the entire booster phase, so a switch isn't always needed. Check the manufacturer's height and weight limits, and only move to backless if your child has exceeded them. In either booster, your child should sit with their back against the vehicle seat and the belt centered across the shoulder and lap for the full ride.

Stay in a convertible car seat as long as possible. A 5-point harness protects younger kids better than a vehicle seat belt, so don't switch until your child has maxed out the height or weight limit of their convertible. Most convertibles harness forward-facing up to at least 65 pounds, which usually puts the switch closer to age 7 or 8.

Look for high-back design with strong side-impact protection. The safest boosters have steel-reinforced bases, rigid LATCH connectors, and energy-absorbing foam in the headrest, plus side-impact pods that absorb crash force. An IIHS "Best Bet" rating is a fast way to shortlist. Safety also includes what your child is breathing, so the safest options skip added flame retardants and PFAS.