Stage 3: Booster Seat

Best practice is to remain harnessed in a tall, high-weight seat until 40lbs AND developmentally ready for a booster (typically age 5 or 6), and able to remain properly seated the entire ride. Not sure if s/he is ready? This article might help you decide. The legal bare minimum for moving into a booster seat is 40 pounds. Children should remain in a booster until they pass the five-step test in the vehicle seat that they will be sitting in, though the legal bare minimum is at least 4’9″ tall OR age 9. Height is most important for proper fit of the adult seat belt.

If your child has outgrown the harnessed seat by height or weight but is not heavy enough or developmentally ready for a booster, look for a taller, higher-weight harnessed seat.

When transitioning to a booster, start with a high-back booster; it gives many kids a better sense of security, provides head support while sleeping, often provides better shoulder belt fit, and is required in vehicles without adequate head and neck support. High-back boosters have head support and belt guides to position the shoulder belt. No back/backless boosters, do not have head support and a child must have in-vehicle head support up to at least the tops of their ears.

Boosters must be used with a lap/shoulder belt and NEVER with a lap belt only. The lap belt should be low and flat across the upper thighs, never riding up on the belly; the shoulder belt should sit across the collarbone, not riding up on the neck or slipping off the shoulder. Please note that 3-in-1 seats most often provide less than optimal belt fit on most children and should not be used as booster seats without carefully considering belt fit. Dedicated booster seats are often inexpensive and many provide excellent fit on most children. The child must remain seated in position at all times, even when sleeping, for the seat belt to protect them.