The best way to determine when your child is ready to stop sitting in a booster seat and use only a seat belt in a car is to use the 5-Step Test detailed below.
Don't make the switch based solely on height or age. Kids aren't ready to make the go from a booster seat to a seat belt until the lap and shoulder belts fit them properly. That typically won't happen until they're about 10 to 12 years old.
State laws also regulate child car seat usage. To learn what the laws are where you live, mouse over your state in this map from the Insurance Institute for Highway Safety (scroll down to the “Restraint use” section).
Because a booster seat protects a child better than a safety belt alone. In the event of a collision, an ill-fitting safety belt, made for an adult, can actually cause injury instead of preventing it.
For instance, if the lap belt rests on your child's tummy (which it's likely to do without a booster), he could suffer stomach, liver, or spleen damage. And if the shoulder belt rests against his neck rather than his chest, he may try to move it under his arm (where it could crack his ribs and damage internal organs) or behind his back (where it offers no protection at all against head, neck, or spinal injuries).
SafetyBeltSafe U.S.A. created the 5-Step Test to help determine if your child is ready to ride with a safety belt only and if the safety belt fits properly. To do the test, buckle your child into the back seat of your car without a booster seat and consider the following:
If you answer no to any of these questions, your child still needs a booster seat. That's true even if your child has passed the height and age requirement for booster seats specified by your state law.
If your child outgrows her current booster seat, replace it with one that has higher weight and height limits. Some booster seats accommodate up to 120 pounds. If she has a long torso, look for a booster seat that's designed to redirect the lap portion of the belt from the tummy to the tops of the thighs.
Be matter of fact about requiring a booster seat whenever your child rides in a car. No exceptions. If your "big kid" still protests that he's too old to sit in a booster seat, here are some ideas to encourage him:
When your child is ready to move to a seat belt alone, don't buy a belt-positioning device to make the seat belt more comfortable for her. These add-ons actually make safety belts less effective.
If your child needs something to make the safety belt snug or to keep the shoulder strap off her neck, she needs a booster seat.
You need both a shoulder belt and a lap belt to protect your child, whether he's in a booster seat or using only a safety belt. If a car has only lap belts:
If none of these options work, consider purchasing another car that has both shoulder and lap belts in the back.
AAP. 2018. AAP updates: Recommendations on car seats for children. American Academy of Pediatrics. https://www.aap.org/en-us/about-the-aap/aap-press-room/Pages/AAP-Updates-Recommendations-on-Car-Seats-for-Children.aspx [Accessed December 2019]
AAP. 2019. Car seats: Information for families. American Academy of Pediatrics. http://www.healthychildren.org/english/safety-prevention/on-the-go/pages/car-safety-seats-information-for-families.aspx [Accessed December 2019]
SafetyBeltSafe U.S.A. 2019. Carseat.org. https://www.carseat.org/index.htm [Accessed December 2019]