There are really only two options when choosing a booster seat harness: a five point restraint or the vehicle's seat belt. Choosing the best booster seat harness option depends on the height, weight, and age of the child who will be riding in the seat as well as applicable laws. In general it is recommended that five point restraint harnesses should be used until the child weighs at least 40 pounds (18.1 kg), although some of the latest designs can accommodate children to maximum weights of 60 to 85 pounds (27.2 to 38.5 kg.). Once the use of the five point restraint harness has been discontinued, it is usually advised for children to continue using the booster seat as a positioning device along with the vehicle's seat belt until they are at least 4 ft. 9 in. (1.45 m) or weigh 100 pounds (45.5 kg).
Booster seats have been shown to reduce the chance of injury to a child during a crash when compared to seat belts alone. The seat belts in motor vehicles are designed to fit adults and can result in injuries to children in crashes due to this fact. Based on this evidence, booster seat use is now required by law in many regions, although there is considerable variation in the mandatory age and weight a child must attain to ride without one. It's important for parents to check the law in their location. For maximum benefit, many organizations involved with child safety advise parents to keep their children in booster seats past the time required by law.
Choosing the best booster seat harness depends on a variety of factors; there is no one size fits all solution. The two available options are the five point harness such as those on infant and toddler seats or the vehicle's seat belt. A child's height and weight are extremely important considerations, since it is important for the harness to fit properly for the most effective protection. When using a five point harness, the straps must begin above or at the height of the child's shoulders, never below, and he or she can weigh no more than the manufacturer's maximum specifications. Once the child is too tall or too heavy, it is time to transition to the vehicle's seat belt with the booster seat.
It is recommended that the five point restraint style of booster seat harness should be used until a child is at least four years old and 40 pounds, and longer if possible. Some seats can accommodate larger children, but they tend to be big and bulky and may not fit in some vehicles. Plus, these may not be the best choice for older or taller children. Once the decision is made to use the vehicle seat belt with the booster seat, there are a variety of options bigger kids are more likely to cooperate in using. Current advice is for children to continue using a booster seat until they are at least 4 ft. 9 in. tall or 100 pounds; as a result, they could be using it until age 10 or older. Obtaining a comfortable seat that's not "babyish" can be extremely important to ensure compliance from older children.