Booster Seats and Seat Belt Safety

You’ve kept your child safe in your vehicle using a car seat—that’s great. Now your child has outgrown the seat and it’s time to upgrade. This sheet tells you how to use booster seats and seat belts to continue to keep your child safe.

Boy sitting safely in booster seat in back seat of car.
A child who has outgrown his or her car seat harness (typically at 40 to 80 pounds) is ready to use a booster seat.

Girl sitting safely in back seat of car with her feet flat on floor and with shoulder and lap seat belts on properly.
The Safety Belt Fit Test at can help you decide if your child is ready to move out of the booster seat.

Upgrading to booster seats

A child outgrows a car seat when he or she reaches 40 to 80 pounds. (Your car seat owner’s manual will give a specific weight, based on the car seat’s harness.) At this point, your child needs to switch to a belt-positioning booster seat. Booster seats raise the child so the car’s seat belt fits properly. To use a booster seat safely:

  • Be sure the shoulder belt lies on the shoulder or collarbone.

  • Be sure the lap belt lies flat across the hips or lap, not on the belly.

  • Use the lap belt and shoulder belt every time your child rides in the booster seat. Never put the shoulder belt under the child’s arm or behind his or her back. This can lead to severe internal injury.

  • Never use a booster seat if only a lap belt is available.

  • Make sure your child uses a booster seat even when riding in someone else’s vehicle.

  • If the vehicle’s seat has no headrest, make sure the booster seat has a high back.

  • Let your child help choose the booster seat. This can help make him or her more willing to use the seat.

Upgrading to seat belts

Is your child ready to move from a booster seat to using just a seat belt? In general, children who are over 4' 9" tall (usually between 8 and 12 years old) can use seat belts safely. The best way to find out if your child is ready is to use the Safety Belt Fit Test. The test helps you check if your child’s legs are long enough and if the lap belt and shoulder belt fit your child securely. For details on how to use the test, go to and search for “Safety Belt Fit Test.”

If using a seat belt:

  • Be sure the shoulder belt lies on the shoulder or collarbone.

  • Be sure the lap belt lies across the hips or lap, not on the belly.

  • Your child's knees should bend over the edge of the seat.

  • Be sure your child is comfortable in this seating position for the whole trip.

  • Children under the age of 13 should sit in the back seat.


Teaching your child to be safe

As your child gets older and rides in cars with other drivers, it is even more important for him or her to understand car safety rules. To keep your child safe:

  • Explain to your child that a booster seat or seat belt will help keep him or her safe in a car crash.

  • Make sure your child understands that he or she must use a booster seat or seat belt in every vehicle, every time. No exceptions.

  • Teach your child how to buckle up in the car.

  • Be sure that older children help set an example for younger kids by buckling up.

  • Don’t forget that your child learns by watching adults, so be sure you use your seat belt every time.

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