How tall does a child have to be before they don't need a booster seat?

A child typically no longer needs a booster seat once they reach a height of 4 feet 9 inches (57 inches) and are between 8 to 12 years old, depending on state laws and recommendations. However, it's essential for the child to be able to sit with their back against the vehicle seat, knees bent comfortably over the edge, and feet flat on the floor. Always check local laws and guidelines to ensure compliance and safety.