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When Should Your Child Use a Booster Car Seat?

Renee Whitmore
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by Renee Whitmore

If you are a parent, you know how exciting milestones are in a child’s life. The first smile. The first steps. The first taste of green beans. The first day of Kindergarten. Benchmarks signifying growth are fun to witness and photograph worthy.

However, one milestone—transitioning into a booster seat—should not be rushed. That leads to our next question: when should your child use a booster car seat?

What is a Booster Seat and Why is it Important?

Graco Backless Booster

First, let’s define what a booster seat is and why it’s needed. Booster seats are the transitional step between a harnessed car seat and a seat belt. A booster seat protects children who have grown out of their car seats but are not big enough to wear a seat belt.

The best booster seats “boosts” and positions a child, so the vehicle’s lap and seat belt fit correctly to best protect the child.

It should be only used in the car’s back seat with a lap-and-shoulder belt never with a lap-only belt. Serious head and/or internal injuries may result from excessive head movement and abdominal injuries from the lap belt.

According to a CHOP 2003 study, booster seats are over twice as effective in reducing the risk of injury when compared with seat belts alone.

So, When Does My Child Need Transitioning to a Booster Seat?

The most apparent indication to signify that it is time to transition your child to a booster seat is that he or she has outgrown the car seat. But how exactly do you know when a child has outgrown a car seat? Here are four factors to keep an eye on:


Every car seat comes with a maximum height restriction. These height limitations vary from seat to seat, so make sure you know what yours is. For many car seats, the height a child needs to be to transition to a booster seat is around 35 inches.

A booster seat is effective until a child reaches the height of 4 feet, 9 inches. This is the height where it is safe to graduate to the built-in lap belt and shoulder harness without assistance.


Just like height, your child’s car seat should have a specific weight limitation, which is typically around 40 pounds. Continue using a booster seat until your child reaches around 80 pounds.


Typically, but not always, a child ages into a booster seat around the time he or she turns five years old. If you have a child who is near five-years-old, look for other indications that it’s time to use a booster seat rather than a car seat. It is more important to look for height and weight indicators than age since children grow at different paces.


Consider the exact fit of your child’s car seat. Does your child look cramped? Do his or her feet dangle way over the seat?  If your child no longer fits comfortably into a car seat, then it is time to move on. After the transition to a booster seat, you’ll will reach a point where your child no longer fits into it either — which is when you don’t need a booster seat at all.

High-Back or Backless Boosters

Graco Affix High Back Booster

When you are looking for a booster seat, you will notice that there are high-back and backless options. What are the differences?

High-back boosters ensure that the shoulder belt is at the correct level for your child’s shoulder. High-back boosters also train your child to sit properly and provides more comfort. Side impact protection features are also included in many high-back boosters.

With a backless booster seat, the child relies on the vehicle’s seat back for head, neck, and back support. Most backless booster seats come with a shoulder belt positioner to adjust the shoulder belt height on the child.

What are the Biggest Booster Seat Mistakes?

Now, let’s look at the most common booster seat mistakes.

Mistake #1: Letting your chisld use a regular seat belt too soon.

A common mistake is that many children are moved out of their booster prematurely.

In fact, according to a 2015 national survey on booster seats from National Highway Traffic Safety Administration, more than a quarter of 4- to 7-year-olds are prematurely transitioned out of their booster.

Seat belts are designed for an adult if they don’t fit properly, serious injuries can occur.

To prevent this mistake, use a booster seat until the adult seat belt fits correctly with the lap portion of the belt fitting low across the child’s hips and the shoulder belt across their sternum and collar bone.

Mistake #2: Allowing children to place the seat belt under their arm or behind their back when using a booster seat.

Injuries can occur if children place their seat belt under their arms or behind their back. A seat belt placed under the arm can cause rib injuries, which can, in turn, may cause additional internal damage. A seat belt behind the back eliminates upper body protection and can cause serious spinal injury or even ejection if an accident were to occur.

Mistake #3: Using a low back booster in a seat without head rests.

Riding in a backless booster seat in a vehicle with no head rests may cause head, neck and spinal injuries in an accident. To ensure the safety of your child, head rests must be used.

The Bottom Line

There is no reason to rush the transition to a booster seat. Before moving to a booster seat, your child should:

  • Be at least 5 years old.
  • Meet the weight and height minimums for the booster seat you’re considering.
  • Be able to sit properly at all times.
  • Meet all the safety requirements of using a shoulder and a lap belt.

It may be tempting, but don’t let others (especially your child!) pressure you into making the switch too soon.

Your child’s safety is at stake; this is a milestone you don’t need to rush!

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About Renee Whitmore
Renee Whitmore
Renee Whitmore is an American college professor and freelance writer from North Carolina. She holds a Bachelor’s Degree in English and a Master’s Degree in English Education. When she is not driving her teenage son to wrestling practice or learning the ins and outs of Fortnite from her younger son, she is working on her first book to be published soon.
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