The Benefits of Keeping the Back on Your Booster Seat

How keeping the back on your high-back-to-backless booster seat may improve your child’s overall safety

Booster seat Photo: John Powers/Consumer Reports

No matter how often they might ask, most kids won’t be ready to use the car’s seat belt alone until they are about 11 years old, according to the American Academy of Pediatrics. Between the time they outgrow their forward-facing harnessed seat and when they’re ready for the vehicle belt, booster car seats are the solution. Boosters raise the child so the vehicle seat belt fits their body correctly, with the shoulder and lap belts positioned to provide optimum protection, while minimizing potential harm. 

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Consumer Reports evaluates three types of booster seats: high-back-only, backless-only, and high-back-to-backless.

CR has long recommended high-back boosters over backless models because shoulder belt fit tends to be better and because the head wings, designed to limit side-to-side head movement in a collision, provide additional comfort for children, especially if they fall asleep. 

Our evaluations of the latest booster models lead us to make a new recommendation: When you have a booster that can be used in either high-back or backless mode: Keep the back on. Here’s why.

Shoulder Belt Fit

In backless mode, a booster seat lacks a shoulder belt guide or a belt positioning clip, which could affect your ability to achieve proper shoulder belt fit for your child. The lack of a guide could mean that the shoulder belt might not fit correctly—midway across the child’s chest and shoulder. Also, children are squirmy, and as they move around, the shoulder belt position can change. Belt clips on backless boosters often won’t maintain proper shoulder belt fit as a child moves around.

Booster seat

Photo: John Powers/Consumer Reports Photo: John Powers/Consumer Reports

Side Wings for Side-Impact Protection and Comfort

Side wings on the high-back booster can serve more than one purpose. While there is no current standard for side-impact protection on child car seats, booster side wings do provide a barrier between the child’s head and the potential vehicle interior contact surfaces. The side wings can also provide a comfortable location for a child as somewhere to rest their head while they sleep, keeping them within the protection of those wings.

Booster seat

Photo: John Powers/Consumer Reports Photo: John Powers/Consumer Reports

Lap Belt Fit

Without the booster seatback attached to the booster cushion, the child sits farther back against the vehicle’s seatback, altering the position of the lap belt. In our fit-to-vehicle evaluations, when the seat is in backless mode, the lap belt is often positioned too far forward—on the child’s thighs, rather than the strong bony protrusions of their pelvis. Consequently, the lap belt fit with booster seats that have had the back removed are often worse than the fit using child seats that are designed to be used only as a backless booster.

Booster seat

Photo: John Powers/Consumer Reports Photo: John Powers/Consumer Reports

Comfortable Posture

Because the lack of the booster back enables the child to sit farther back on the booster cushion, it also becomes more likely that the child’s knees might not bend over the edge of the cushion. This may cause the child to slouch for comfort, which risks shifting the lap belt onto the soft tissue of their abdomen, making the child more prone to injury.

Booster seat

Photo: John Powers/Consumer Reports Photo: John Powers/Consumer Reports

Seating Position

Not all rear seating positions have head restraints that are tall enough to provide adequate protection, and some have none at all, which could result in a neck injury if the car is involved in a collision. A child in a backless booster must sit in a seating position where there is a head restraint that can adjust with them as they grow, reducing the potential for a whiplash injury. This means the child may need to be positioned in an outboard seat, not the middle spot. High-back boosters, however, can be used even if the vehicle head restraint is too low or nonexistent because the booster’s seatback provides some level of head protection.

With any child seat, don’t be in a rush to move your child to the next seat. And for any booster seat, your child’s ever-changing stature and the geometry of your vehicle’s seats and seatbelts can all alter belt fit. Use this booster seat quiz to determine whether your booster seat is providing a good fit or if your child is ready for the vehicle seatbelt alone. 

Emily A. Thomas, PhD

At Consumer Reports, I've found the perfect blend for my love of injury biomechanics, forensics, and kids as an automotive safety engineer for child passenger safety. For me there's no greater reward than helping families keep their little ones safe and coming home to put my advice into practice with my own precious little boy. Between church activities, my big Indian family, and exploring new places with the hubby and baby—my life and my heart are full.