What determines when a child can stop using a booster seat?

The proper time for a child to stop using a booster seat is determined by their ability to fit comfortably and safely in an adult seat belt. A child should remain in a booster seat until the vehicle's seat belt fits them correctly, which typically means that the lap belt lies snugly across their upper thighs and the shoulder belt crosses the chest and shoulder. This ensures that the seat belt system is effective in the event of a crash, providing the necessary protection.

While age, weight, and height are relevant factors in determining a child's readiness for a booster seat, they do not alone guarantee a proper fit for the seat belt. Using a booster seat until the seat belt fits correctly is crucial for the child's safety in the vehicle.