Boosters and Lap Belts

Belt-positioning booster seats are not designed to work with lap-only belts, as they cannot pass FMVSS 213 head excursion requirements when used this way. While using a booster seat with a lap belt may reduce the likelihood of abdomen injury (Kirley et al. 2009), it has the potential to increase the likelihood of head injury, which should be considered higher priority because of the greater potential for serious long-term consequences. A booster positions a child’s head higher, and with a highback booster, more forward than a child sitting directly on a vehicle seat. Without torso restraint provided by a shoulder belt, the head position of a child using a booster increases the risk of head contact compared to a child on a vehicle seat. With respect to prevention of head contact, it is better for a child to sit directly on the vehicle seat when only a lap belt is available than to sit on a belt positioning booster.