Choosing the Right Car Seat for Your Older Child

Standard lap and shoulder belts do not fit a child until they are about 4’9” tall and weigh around 80 pounds. An ill-fitting seat belt may ride up and cause serious injury in a crash.

A booster seat protects the child’s upper body with either the shoulder belt or a shield. In addition to helping a child sit up straight and allowing their legs to bend normally, the booster seat also raises the child so that the vehicle lap/shoulder belt fits properly.

A child should stay in a safety seat with a full harness until the seat is outgrown, usually about 40 pounds. When a child’s shoulders are above the top set of strap slots, it is time for a booster seat.

Why use a booster seat instead of a safety belt?

  • Most 40-pound children are not big enough to fit lap and shoulder belts properly.
  • A belt that rides up on the tummy could cause serious injury. The adult lap and shoulder belt normally does not fit a child until they are about 4’9” tall and weigh approximately 80 pounds.
  • Many young children do not sit still enough or straight enough to keep lap belts low across their thighs.
  • Boosters are comfortable for children because they allow their legs to bend normally. This also reduces slouching, one cause of poor lap-belt fit.

What features are available in booster seats?

  • Boosters without shields. Because these are used with the vehicle lap/shoulder belt, they are also called “belt-positioning boosters." Some have high backs that give head support for taller children. Some booster seats are built into vehicle seats.
  • Boosters with removable shields. Use without the shield to make lap and shoulder belts fit right. Shield boosters are not currently approved for children weighing over 40 pounds. A child who has outgrown the convertible seat, yet weighs less than 40 pounds can be moved into a high-back booster with a harness. Once the child reaches 40 pounds, the harness is removed and the seat is used with the adult lap and shoulder belt as a belt-positioning booster.
  • High-back boosters with removable shields and harnesses. Children under 40 pounds who have outgrown a convertible seat can be moved into a high-back booster with a harness. (Some booster seats have removable harnesses.) Shield boosters are currently not approved for children weighing over 40 pounds. Over 40 pounds, use boosters without the shield and harness. Make sure the adult lap and shoulder belts fit correctly. Most have a clip or strap to hold the shoulder belt in place.
  • Child Seat/Booster: This seat has a 5-point harness. If you remove the harness it becomes a belt-positioning booster (right) to use with a lap/shoulder belt for a larger child.

Which booster is best?

  • The belt-positioning booster is the best choice if your car has combination lap/shoulder belts in the rear seat.
  • Use a booster with a high back if there is no head restraint for the child.
  • The booster with a high back and a removable harness provides the most options in many vehicles. Check the label for the weight limit on the harness.
  • Children who reach 40 pounds before age 3 may not be mature enough to stay seated properly in a belt-booster. A vest that uses the belt system and a tether strap would be an option in this situation.

How long should the booster be used?

As a child grows and learns to sit comfortably without slouching, a simple check will tell you if it is time to remove the booster seat and use vehicle seat belts:

  • Can the child sit with his/her back against the vehicle seat back cushion, with knees bent over the vehicle seat edge and feet on the floor?
  • Does the lap belt fit low over the child's upper thighs and the shoulder belt fit snugly across the chest, not across the neck or face? If so, the child is usually ready for the adult lap and shoulder belt.

How should a lap belt fit?

  • The lap belt should fit low over a child's upper thighs. Keep the belt snug. If the lap belt rides up onto the tummy, it could cause serious injuries in a crash.
  • The shoulder belt must fit snugly across the chest. If the shoulder belt goes across the neck or face, raise the child with a belt-positioning booster seat.
  • If you have the kind of shoulder belt that stays loose when it is pulled out, make sure there is no more than one inch of slack. Teach your child to tug at the shoulder belt to take up excess slack.
  • Seat belt fit is crucial toyour child’s protection.
  • Never put a shoulder belt under the child’s arm or behind the back. Either of these kinds of misuse could cause serious injury in a crash. Some devices advertised to improve belt fit for older children and adults are not covered by government standards. They may help improve comfort but allow too much slack in the shoulder belt or cause the lap belt to ride up. Boosters are a better solution for children.
  • Straps fit low on the top of the legs and across the chest.

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