Your Big Kid Still Needs a Booster Seat (Yes, Really!)


Your big kid needs a booster. Yes, really.

You’ve been diligent about buckling your child in, first in their baby “bucket,” then their convertible seat, and finally their booster. Now your little one is not so little anymore–he’s over four feet tall, styles his own hair, and his shoes approach yours in size. Or she insists that she’s a “big kid,” car seats are for babies, and all her friends are riding without one. At this point, it’s tempting to let your child graduate from what seems like the last remnant of early childhood–their car restraint. This post will explain when your child will be truly ready to use the seat belt without a booster and why you should resist the urge to ditch the booster before that time.

What do boosters do?

Seat belts are designed to fit adults and tested using “dummies” between 5’/110 lbs to 6’2”/ 223 lbs. Booster seats literally boost the child up so that the shoulder portion of the seat belt fits their torsos properly without cutting into their neck and the lap belt stays low across the hips. In adults, the anterior superior iliac spine helps to keep the lap belt in place. But this part of the hip does not turn into bone until puberty, so without a booster, a lap belt is more likely to slip above a child’s hips onto their torso. (This is why your 4′ 11″ grandmother doesn’t need a booster.)

Your Big Kid Still Needs a Booster Seat (Yes, Really!)What are the risks of not using a booster?

Children who are riding using only a seat belt before it fits them properly are at significantly increased risk of injury and death–around 60% higher. Improper fit of the lap and/or shoulder belt can cause “seat belt syndrome,” including lacerations (tearing) of liver, spleen, or bowel, a ruptured bladder, and internal bleeding as well as vertebral fractures and other damage to the spine. To be more comfortable when it cuts into their necks, children often put the shoulder belt behind their backs or under their arms. Without the shoulder belt, their torsos ‘jack-knife’ in a crash, putting enormous forces on their spines and necks.

Not using a booster also exposes you to legal risk. In New Mexico, state law requires that children must use an appropriate restraint until the seat belt fits them correctly and that all children under 60 lbs (regardless of height or age) must be in a restraint. In some localities, more stringent ordinances also exist. New Mexico is a “primary enforcement” state where you can be stopped and ticketed for violating the seat belt law for yourself or your passengers without any other violations.

When can my child stop using a booster?

The exact time when children can stop using a booster varies according to their body proportions and the vehicle they are riding in. Because of variations in seat belt geometry in different vehicles, your child may be ready to ride without a booster in one car, but not another. To safely use a seat belt alone, children need to pass the so-called “five-step-test”:

1. Sitting in the seat with their bottoms and torsos all the way against the seatback.
2. Knees are bent at the end of the seat.
3. The lap belt lies across the thighs/hips, not the tummy.
4. The shoulder belt crosses their shoulder rather than their neck.
5. They can stay in this position for the entire length of the trip, without slouching or otherwise getting out of position.

Most children need to be at least 4′ 9″ before all of the above are true. But even taller children may still need a booster. Some children need a booster until they’re 10-12 years old.

What do I do if my child is larger than average, but doesn’t pass the five-step-test yet?

Several booster models are available for children who weigh more than 100 lbs (a common weight limit for boosters). They can be bought for as little as $15, though you may need to purchase them online. The Chicco GoFit, Evenflo Amp and Big Kid/Big Kid Sport, and Nuna Aace all accommodate children up to 110 lbs. Britax Parkway, Diono Monterey and Hip, and Peg Perego Viaggio 120 fit children up to 120 lbs.

What about carpooling?

Most no-back boosters are lightweight, easy to carry, and some fold so they can fit in a backpack. The Graco TurboBooster TakeAlong, the BubbleBum inflatable booster, and the RideSafer travel vest (among others) are all designed with portability in mind.

It’s easy to keep a spare booster in your vehicle in case you are transporting your child’s friends. Every child who needs to be in a restraint should be in one for every trip as improperly restrained passengers can injure others in the vehicle as well as themselves.

What if my child complains about having to use the booster?

Most children respond well to a fact-based explanation of why they need to use a booster (again):

1. Seat belts are made for adults. Using them before you’re the right size is like wearing clothes made for adults. This doesn’t make you a baby any more than wearing clothes that fit your body makes you a baby.
2. You will be able to use a seat belt when your body is the right size. We can’t control how your body grows, but we need to keep it safe.
3. Using a booster helps protect you from injuries that seat belts can cause if they don’t fit properly.

Depending on your child, you may be able to support your argument by showing them videos and other visuals that demonstrate these points.

The Safety 1st Incognito is a ‘discreet’ booster with a low profile and no sides. It is available in colors that match many car interiors. It is a good choice for children who insist they cannot be seen riding in a booster.

What else can I do to protect my child in the car?

Make sure the driver and every passenger correctly use a seat belt and appropriate restraints for every trip. Children are less likely to use a seat belt if the driver is not using one, so lead by example.

Children 12 and under should ride in the back seat at all times. Airbags get activated at speeds of 200 miles per hour even in relatively minor crashes, and their force can seriously injure and potentially kill a child. Young children riding in the front passenger seat have a 30-50% higher risk of injury even when using a seat belt.

About the Author

A former nomad who has lived all over the US as well as in Germany, Scotland, and New Zealand, Vanessa Will now makes her home in Albuquerque with her spouse, an Albuquerque native, and two daughters, 9 and almost 7. She is a certified Child Passenger Safety Technician who volunteers for Safer New Mexico Now. By day, she works in research administration at the University of New Mexico.

Originally published August 2018.

The opinions expressed in this post are those of the author. They do not necessarily reflect the official policy or position of ABQ Mom, its executive team, other contributors to the site, its sponsors or partners, or any organizations the aforementioned might be affiliated with.