Why 3-Year-Olds Have No Business Riding In Booster Seats


Is a 3-year-old safe in a booster?

I see this less frequently than in years past, but it’s still happening all across America. Parents are graduating preschool-age children into booster seats too quickly. The problem is, it’s not a “graduation”. It’s a demotion in safety. And it’s putting young children at risk for serious and possibly fatal injuries in a crash.

Here are some of the main reasons why 3-year-olds (and even many 4-year-olds) have no business riding in a booster seat in the car:

  1. 3-year-olds (and young kids, in general) lack the maturity to stay properly seated for every ride in a booster seat
  2. Even though some booster seats are rated down to 30 lbs., it is generally accepted that children under 40 lbs. are best protected in a seat with a 5-pt harness
  3. Some booster seats do not position the seatbelt optimally on the body of an average 3-or-4-year-old which could lead to internal injuries in a crash
  4. Many boosters seats have a seating depth (front-to-back) that is too deep for the shorter legs of a younger child. If the child has to slouch or scoot forward to bend his/her knees over the edge of the booster, that will promote poor seatbelt fit which increases injury risk.
  5. Having a 3-year-old in a booster is illegal in some states (like New York), although there may be exemptions

Think of it this way – when your child rides in a carseat with a 5-point harness, the responsibility for the child’s safety rests on you, the parent or caregiver, to make sure that the child is safe in the vehicle. It’s the parent/caregiver’s responsibility to make sure the seat is installed tightly and the harness straps are snug around the child. The child is responsible for nothing. God forbid, in case of a crash, the child should be in the proper position to allow the carseat to do its job.

Now, once your child transitions to a belt-positioning booster seat using the vehicle seatbelt – that responsibility for the child’s safety switches to the child. The booster seat can’t do its job if, at the moment of impact, the child has leaned over to pick up something off of the floor of the car. Or leaned over to mess with their little brother or sister. Or fallen asleep out of position. Or put the shoulder belt under their arm. Etc, etc. Booster seats are for children who are mature enough to sit still and stay in the proper position. And they have to be able to stay in that proper position for the entire ride, every ride. Awake or asleep.

I know there are some 3-year-olds who can do that but the vast majority cannot. 3-year-olds (and many 4-year-olds) are just too wiggly! Most are not ready yet for the extra freedom that a booster provides. Usually, by kindergarten age, most kids are ready to start “booster training”. But if your kid is still a wiggle worm with no impulse control – then you should continue to use a seat with a 5-point harness. Just make sure it’s a seat that your kid still fits in.

There are a still a few forward-facing carseats with a 5-pt harness that have low top harness slots and a 40 lbs. weight limit on the harness. Those seats will be outgrown much more quickly by weight or by height. But there are many more seats on the market today with a 5-point harness rated up to 50 or 65 pounds that also have tall top harness slots to keep those preschool-age kids safely in a 5-pt harness for a few more years. And many of them can also be used in booster mode (without the harness) once the harness is outgrown. We call those “Combination Seats” (pictured below) because they combine a forward-facing 5-point harness seat with a booster seat.


For more information on appropriate seats for preschoolers, please see our list of 2019 Recommended Combination Seats.


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