Child Weight Requirements for Seat Belts

As of January 2010, the leading cause of death for children ages 3 to 6 and 8 to 14 is motor vehicle crashes, according to the National Highway Traffic Safety Administration. While each state has its own laws regarding child seat belts (see Resources), 47 states require booster seats or other appropriate devices for children who have outgrown their child safety seats but are still too small to use an adult seat belt safely. For vehicles made after 2000, the LATCH system is recommended instead of a seat belt for proper installation. The American Academy of Pediatrics (AAP) and Federal Motor Vehicle Safety Standards provide guidelines to meet weight requirements for child seat belt use that also meet or exceed all state requirements.


Infant car seats vary by manufacturer. Read the manual or contact the seat manufacturer for the weight and height maximum for the infant seat. When the infant has outgrown the infant seat, switch to a rear-facing convertible seat. Infants must ride rear-facing in an infant seat until they have reached at least one year of age and weigh over 20 pounds.


Keep the toddler rear-facing in a convertible seat until she outgrows the manufacturer’s specifications. Place the toddler in a front-facing seat from the following options: convertible seats, a combination seat set with harness, built-in seats in newer vehicles (check your car manual for guidelines), and travel vests. The toddler needs to stay in one of these seat systems until she outgrows it. At a minimum, a toddler must stay in a harness system until she weighs 40 pounds. Check the manufacturer guidelines, as some allow children to remain safely harnessed until they weigh 80 pounds.

School Age Children

Seat belts were designed for adults. A child should move into a booster seat after outgrowing toddler seats until the adult seat belt fits correctly. The AAP instructs to check height at this point and not weight. The recommended minimum height is 4’9” is.

Test if the child is ready by making sure the shoulder belt lies across the middle of his chest; if it is on the shoulder or neck, he’s not ready. The lap belt must rest on the thighs and not the stomach. Check individual state laws regarding booster seat use (see Resources).