There is more choice than ever for finding a booster seat that correctly fits your child according to a new report from the Insurance Institute for Highway Safety (IIHS). The Institute has released their 4th annual list of the best-fitting booster seats for children age 4 to 8 years old and found 31 models that have been designated as IIHS Best Bets, which means they offer the best potential of correctly positioning a vehicle’s seat belt on a child in a variety of vehicle types.

The IIHS ratings are based solely on how well each booster seat positions the lap and shoulder belt, its primary function, and are not an assessment of crash performance or vehicle fit. In addition to a seats ability to provide a proper belt fit in a variety of vehicles, we include both crash protection and an ease-of-use assessment in our own evaluations of booster seats. Consequently you may find some differences between the ratings.

A well-fitting booster should put the lap portion of the seat belt flat across a child’s upper thigh and the shoulder belt at mid-shoulder. A check that you should make with your own child in your own car when you select a booster seat (see questions for assessing booster fit below). In fact, the largest group of seats in the IIHS ratings are those that they designate as “check fit” meaning their ability to provide a good fit will likely need to be determined on a case-by-case basis.

Eighty-three boosters were evaluated this round, which is 11 more than last year. Thirty-one models overall were Best Bets and five are Good Bets. However six are “Not Recommended” because they do a poor job of providing proper belt fit. One notable newcomer to the list is a model called BubbleBum, which is an inflatable seat that makes it convenient and portable to use on vacations, taxis, or in car pools.

There are 21 boosters that show up twice on the list, as they are dual-use seats--meaning they can be used as a highback or backless seat. Our own tests and a review of the IIHS Best Bets shows that highback models tend to offer the best potential over backless versions of providing a proper belt fit.

Boosters have improved considerably the past few years. When IIHS first started conducting these tests in 2008, there were only 10 Best Bets and last year the ranks climbed to 21 after manufacturers started utilizing the IIHS test protocols when designing and updating their seats. A good thing for us as consumers.

The 2011 IIHS Best Bets:

Britax Frontier 85
Britax Frontier 85 SICT
Britax Parkway SGL (highback mode)
BubbleBum
Chicco KeyFit Strada (highback mode)
Clek Oobr (highback mode)
Cosco Pronto (highback mode)
Cybex Solution X-Fix
Diono/Sunshine Kids Monterey (highback mode)
Eddie Bauer Auto Booster (highback mode)
Evenflo Big Kid Amp
Evenflo Big Kid Sport (backless model)
Evenflo Maestro
Evenflo Symphony 65 e3
Ferrari Dreamway SP (highback mode)
Graco Argos 70 (highback mode)
Graco TurboBooster—Baldwin (highback mode)
Graco TurboBooster Elite (highback mode)
Harmony Cruz Youth Booster/Harmony Carpooler
Harmony Dreamtime (backless mode)
Harmony Dreamtime (highback mode)
Harmony Olympian/Secure Comfort Deluxe
Harmony Youth Booster Seat
Kids Embrace Dale Earnhardt, Jr.
Maxi-Cosi Rodi XR (highback mode)
Recaro ProBooster
Recaro ProSport
Recaro Vivo
Safety 1st Boost Air Protect (highback mode)
Safety 1st S1 Rumi Air
The First Years B570 Pathway

See the full list at www.iihs.org.

To conduct this test, the IIHS used a crash-test dummy representing the average six-year-old child. Engineers measured how well each of the 72 booster seat models positioned the three-point lap and shoulder belts on the dummy under four conditions spanning the range of belt configurations in a variety of vehicle types.

The IIHS test provides an important assessment when choosing a booster seat and educates parents on how belts should fit and what to look for. The IIHS test is based on fit to a dummy that represents an average sized six-year-old child, but as we know, children and cars come in all shapes and sizes, so it’s important to do your own assessment to make sure the belt properly fits your child in their booster. If you determine that the belts fit fine and the seat is positioned properly, then it should provide good protection. Just as we recommend to try a car seat in your car before you buy, it’s also important to try out your child in the seat, as well.

When assessing booster fit, ask these key questions:

• Does the booster seat position the shoulder belt across the clavicle/collar bone, approximately mid-way between the neck and shoulder?
• Does the booster seat position the lap belt low and flat across the hips/top of the thighs?
• Does either the booster seat or vehicle head restraint provide some support behind the child’s head?
• Is your child comfortable and not tempted to move the belts or themselves out of position after a period of time?

All states have laws for the use of child restraints, but some are stricter than others. Currently, most states have laws that cover children up until age seven, but many others don’t require child restraint use above the age of five. Variations and confusion in booster seat state laws, seat cost and inconvenience, and child discomfort are reasons why children five- through seven-years old are not always restrained in booster seats—but they should be as they can help reduce injuries in a crash. See "Tough booster laws for older children help reduce crash injuries".

Consumer Reports recommends booster seats be used until the child can comfortably and safely fit the vehicle belts alone. If you’re unsure if your child fits the vehicle belts without a booster, ask the same questions as above but without the use of the booster.

To provide the best protection, the National Highway Traffic Safety Administration (NHTSA) recommends using a booster seat for children until they are at least eight years old or 4’9” tall. Also, all children under age 13 should ride in the rear seat.

For more information on how to choose the right infant, convertible, or booster seats, see our latest Ratings and buying advice. Also, check out our video on installing booster seats. For more on driving with kids, see our Kids and Car safety special section.