Is a 3-Year-Old Safe in a Booster Seat?
The short answer is no.
3-year-olds have no business riding in booster seats, and we’re going to explain why.
It’s still happening all across America. Parents and caregivers are moving preschool-age children into booster seats prematurely. The problem is, it’s not a “graduation”. It’s a demotion in safety, and it’s putting young children at risk for serious injuries in a crash.
What is a Booster Seat and How Does it Protect?
Technically, a booster seat does NOT have an integrated 5-point harness. It uses the vehicle’s lap/shoulder seatbelt to restrain the child. A booster simply raises the child up (literally, a “boost”), so that the vehicle seatbelt, which is designed to restrain and protect an adult in a crash, fits the smaller body proportions of a child. When a child rides in a booster seat, the vehicle is mainly responsible for restraining and protecting the child in a crash.
The downside is that a lap/shoulder seatbelt is a 3-point restraint system which has limitations and isn’t as protective as a 5-point harness, especially in certain types of crashes like side-impacts and rollovers. This is why professional drivers and racers typically use a 4-point or 5-point restraint system.
Is It a Booster? Confusing Marketing Terms Are… Confusing
There are car seats on the market that use the word “booster” in their marketing. You’ll see car seats that are called “Harnessed Boosters”, “Harness + Booster”, 3-in-1, or All-in-One. All of these types of seats are generally appropriate to use for a typical 3-year-old child, but only when used with the 5-point harness.
Most of these seats have a 5-point harness that is rated up to 50 or 65 pounds, and most also have tall top harness slots to fit preschool-age kids. Once the child is older and the harness has been outgrown by height or weight, the seat can be converted to booster mode (without the harness) and used with the seatbelt over the child.
Reasons Why 3-Year-Olds Should NOT Ride in a Booster
All booster seats for sale in the US have a minimum weight requirement of 40 lbs., and most have a minimum age requirement of at least 4 years old. Check the owner's manual that came with the seat for confirmation.
Young children, in general, lack the maturity to stay properly seated for every ride in a booster seat (see more about maturity below).
Safety experts agree that children under 40 lbs. are best protected in a seat equipped with a 5-point harness.
Some booster seats may not position the seatbelt properly on the body of a 3-year-old child, which could lead to seatbelt-related injuries in a crash.
Having a 3-year-old in a booster is illegal in most states, although there may be exemptions.
While booster seats are appropriate and necessary for older children who have outgrown the 5-point harness on their carseat but still need a “boost” to fit properly in an adult seatbelt, they generally offer less protection in very serious crashes.
Maturity Matters
Think of it this way – when your child rides in a car seat with a 5-point harness, the responsibility for the child’s safety rests on you as the parent or caregiver. It’s YOUR responsibility to make sure that the car seat is installed correctly and the harness straps are snug around the child. In this scenario, the child is responsible for nothing. In a crash, the child should be in the proper position to allow the car seat to do its job.
Once your child transitions to a booster seat and is secured 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 moved out of position. Or put the shoulder belt under their arm. Or fallen asleep out of position. Booster seats are for children who are mature enough to sit still and remain in the proper position. And they have to be able to stay in that proper position for the entire ride. Awake or asleep.
I understand that there are a few rare 3-year-olds who are mature enough to be responsible for their own safety in a moving vehicle, but the vast majority are not. 3-year-olds (and many 4-year-olds) are just too wiggly! Most are not yet ready for the extra freedom that comes with riding in a booster seat.
By kindergarten age, many kids are large enough and mature enough to start the transition to a booster seat. However, 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 that your child is still within the weight and height limits of the seat. Very often, kids outgrow their car seat by height before reaching the weight limit.
But What About Giant 3-Year-Olds?
We’re parents too, and we understand that some 3-year-old children are really tall and/or heavy for their age and may have legitimately outgrown their harnessed carseat. There are also a few car seats on the market that are easily outgrown because they are only rated to 40 lbs. with the harness and/or they have very low maximum harness heights.
If your 3-year-old child has legit outgrown their current car seat, look for a car seat with a 65 lb weight limit that has tall top harness slots. If you don’t need a seat that can be used rear-facing, some of our favorite forward-facing “combination” seats include the Chicco MyFit, and the Graco Nautilus 2.0. If you prefer a long-lasting “All-in-One” seat with tall top harness slots that can be used rear-facing, forward-facing, and as a booster - we recommend the Britax One4Life Slim and the rotating Evenflo Revolve360 Extend.