What is the appropriate age to start using a belt-positioned booster seat?

The appropriate age to start using a belt-positioned booster seat is when a child outgrows their harnessed car seat. This transition occurs because a booster seat positions the vehicle's seatbelt properly across a child's body, ensuring safety during travel. When a child has reached the height or weight limits of their harnessed seat, it usually indicates that they are ready for the next step in car safety.

Harness seats are designed to safely secure younger children, typically those who are between the ages of one and four. Once a child exceeds the weight or height guidelines for these seats, it's important to switch to a booster seat, which is meant for older children and helps in using the car’s seat belt correctly.

Other options such as starting to use a booster seat based solely on weight, age, or whether they can sit in a regular seat do not take into account the critical factor of the child’s current car seat equipment and the effectiveness of the restraint system. Each child is different in growth patterns, and the transition to a booster should be based on individual readiness rather than generalized criteria.