Originally posted here.
The legal answer to this question comes from the state in which you live. For the State of Ohio, booster seat law states a child should remain in a booster seat until they reach 8 years old or 4’9” tall, whichever comes first. The AAA has child restraint laws listed alphabetically by state for reference.
Because the legal age to ride without a booster is 8, we see a lot of children transitioning out of their booster seat right at their 8th birthday. But most child passenger safety experts – myself included – advise families to keep kids in a booster until they reach 4’9” tall.
This height may seem tall, but it is the height determined to be the point at which the vehicle’s seat belt begins to fit like it would an adult. Seat belts, when first designed, were made for adults, not children, and therefore do not fit children properly.
A proper seat belt fit means the lap belt sits low on the abdomen, across the pelvic bone and hips. It also means the shoulder belt is angled across the chest, collar bone and shoulder. It should not rub against the child’s neck. The official name for boosters is “belt positioning booster seats,” and this is because the booster lifts the child into a position that allows the seat belt to fit properly.
If it doesn’t fit properly, the child could be injured more seriously in a crash. A lap belt across the stomach instead of hips can cause internal abdominal injuries in a crash. Additionally, a shoulder belt that has been placed behind the child’s back because it’s rubbing his or her neck cannot keep the child against the back of the seat in the event of a crash.
Bottom line, keeping children in booster seats longer than 8 years old is a good thing. One study found that children riding in booster seats are 45% less likely to be injured in a crash than a child just using a seat belt.
The child may be as old as 12 before the seat belt fits him or her without the booster, but it’s important to wait until that point for each child. If you think your 8-12 year old is getting close, you can do this five step test to determine if they’re ready to ride without the booster. If you answer “NO” to any of these questions, we suggest you continue to use the booster seat and try again in 3 or 4 months.
The five step test:
- Does the child sit all the way back against the auto seat?
- Do the child’s knees bend comfortably at the edge of the auto seat?
- Does the belt cross the shoulder between the neck and arm?
- Is the lap belt as low as possible, touching the thighs?
- Can the child stay seated like this for the whole trip?
And if you ever see your child put the shoulder belt behind his or her back, ask that they put it back immediately. And if it’s an ongoing issue, it may be indication that you need to pull the booster back out and use it for a while longer.