Backless booster
A simple raised cushion with no back or headrest. It needs the vehicle seat to already provide head support and a good shoulder belt anchor point. Lighter, cheaper, and easier to move between cars.
Plain-English explainer
What Is a Booster Seat?
A booster seat is a car seat with no harness. It raises a child so the vehicle's own seat belt fits correctly, instead of restraining the child directly.
Quick answer
A booster seat raises a child so the adult seat belt fits correctly; it has no harness of its own
A booster seat is a car seat for older children that does not buckle the child in directly. Instead, it lifts and positions the child's body so the vehicle's existing lap-and-shoulder seat belt crosses the right places: low across the hips and upper thighs, and across the middle of the shoulder and chest rather than the neck or face.
That is the one thing every booster seat has in common, whether it is a simple backless cushion or a high-back model with a headrest. The belt itself, not the booster, restrains the child in a crash. The booster's job is positioning, not restraint.
If your child still needs a booster, a backless model such as the Graco TurboBooster 2.0 Backless Booster Car Seat is the simplest way to meet the rule once they have vehicle head support (a lower-cost backless option works too); younger children often do better in a high-back booster. Not sure which? Use the seat finder, or run the 5-step belt fit test before dropping the booster. Shopping links — see our affiliate disclosure.
Car seat vs. booster
How a booster seat differs from a car seat
Parents often use "car seat" and "booster seat" loosely, but they work differently. An infant seat or a convertible car seat used forward-facing has a built-in harness with straps that go over the shoulders and buckle at the chest and between the legs. The harness itself holds the child in place, independent of the vehicle's seat belt.
A booster seat has no harness. It relies entirely on the vehicle's own adult seat belt. That is why a child generally needs to outgrow the forward-facing harness seat, by height or weight, before moving to a booster: the harness is more protective while it still fits, because it restrains the child directly rather than depending on belt fit and the child sitting correctly.
How it works
Why belt position is the whole point
An adult seat belt is designed for an adult-sized body. On a smaller child sitting directly on the vehicle seat, the lap belt tends to sit across the soft stomach instead of the hip bones, and the shoulder belt tends to cross the neck or face, or get tucked behind the back or under the arm out of discomfort. Both of those positions are dangerous in a crash.
A booster raises the child's seating height and, on many models, guides the belt path with built-in belt guides. The result: the lap belt lands low across the upper thighs, and the shoulder belt crosses the middle of the shoulder and chest. That correct path is what actually protects the child; the cushion and plastic shell of the booster do very little in the crash itself.
Types
Backless vs. high-back boosters
High-back booster
Adds a headrest and side wings, plus a built-in shoulder belt guide. Useful in vehicles with low seat backs, for children who need more side support, or for booster riders who tend to fall asleep in the car.
2-in-1 / combination booster
Converts from a forward-facing harness seat to a belt-positioning booster as the child grows, or from high-back to backless. One seat spans two stages instead of buying twice.
Shopping picks
Quick picks: booster seats that match this page
Shopping links, separate from the law and safety guidance on this page; they do not change what the state requires. See our affiliate disclosure.
Backless booster
Graco TurboBooster 2.0 Backless Booster Car Seat — the best-selling backless option, with cup holders, for a child who has vehicle head support.
High-back booster
Graco TurboBooster 2.0 Highback Booster Car Seat — for a child who still needs head and side support, or a vehicle seat with a low head restraint.
Not sure which type fits your child? Use the seat finder — enter age, height, and weight to see the stage and a matching seat.
Do I need one
Does my child need a booster seat right now?
Two separate questions answer this. First, the legal one: does your state's child passenger law still require a booster or child restraint for your child's age, height, and weight? Rules vary by state; use the state law hub to check yours.
Second, the safety one, which matters even after the legal minimum is met: does the adult seat belt actually fit your child correctly without a booster? Run the belt fit test on the booster seat age guide, or use the seat finder to get a quick read based on age and height.
Common confusion
"Booster seat" searches that are not about child car seats
Not everyone searching "what is a booster seat" is asking about children. A viral notice circulating in 2026 falsely claimed that adults under a certain height (5'2" or 5'4" depending on the version) are required by law to use a booster seat while driving. No U.S. state has such a law. If that is what brought you here, read the adult booster seat law fact check for the full state-by-state breakdown.
Separately, "booster seat" sometimes gets confused with a high chair booster (a child's dining seat) or a general seat cushion. This page, and this site, are about the car seat used for vehicle travel.
Booster seat requirements
The full framework: age, height, weight, state law, and belt fit in one guide.
Read requirementsAge guide
When kids typically start and stop using a booster, plus the 5-step fit test.
Read age guideState laws
Compare booster seat age, height, weight, and fine rules for all 50 states.
Open laws hubSources
National guidance used for this page
NHTSA car seats and booster seats, CDC child passenger safety prevention, AAP car safety seats guidance, and FMVSS 213 (49 CFR 571.213), the federal standard booster seats are tested against.
Not legal advice
This page explains what a booster seat is and how it works. For your state's specific legal requirement, use the state law hub linked above.
FAQ
Common Questions
What is a booster seat?
A booster seat is a child car seat that has no internal harness. It raises and positions a child so the vehicle's own adult lap-and-shoulder seat belt fits correctly, instead of restraining the child directly the way a harnessed car seat does.
How is a booster seat different from a car seat?
"Car seat" usually means an infant or convertible seat with a built-in harness that buckles the child in directly. A booster has no harness. It works with the vehicle's seat belt, lifting the child so the belt crosses the shoulder and chest instead of the neck, and stays low on the hips instead of the stomach.
Do I need a booster seat for my child?
Most children need a booster after they outgrow a forward-facing harness seat and before the adult seat belt fits them correctly on its own, which is often somewhere between ages 4 and 12 depending on the child's size. Check your state's booster seat law and the seat belt fit test to decide.
What's the difference between a backless and a high-back booster?
A backless booster is just a raised seat cushion; it needs a vehicle seat with its own head support. A high-back booster adds a headrest and side wings, which helps route the shoulder belt and gives head support in vehicles that lack it.
At what age do kids stop needing a booster seat?
There is no single national age. Booster use typically ends once a child passes the seat belt fit test, commonly around ages 9 to 12, though several states set an earlier legal minimum such as age 8 or a height of 4'9".
Do adults ever need a booster seat?
No. Booster seats are child restraint devices. Viral claims that adults under a certain height must use a booster seat are false; see the adult booster seat law fact check for the state-by-state breakdown.