From around 4 years old and 40 pounds to 8-12 years old and 80-100 pounds (depending on the seat), and at least 4'9". A booster seat positions your child so that your vehicle's lap-and-shoulder belt fits properly.
1. If your car has low seat backs or no headrests, use a high-back model (not pictured here). These seats can also offer extra side impact protection, though it can be a struggle to keep older kids in them.
2. Always use both the lap and the shoulder belt, and never allow your child to put the shoulder strap behind his back or under his arm.
3. The shoulder belt should cross his shoulder midway between the neck and the arm. To get the right placement, use your vehicle's built-in shoulder-belt height adjuster or the shoulder-belt positioner that comes with your seat.
4. The lap belt should rest below your child's hip bones (not on his abdomen) and touch the top of his thighs.
Ready to lose the booster?
Yes, if all of these boxes are checked:
Your child can sit all the way back against the seat.
He can bend his knees comfortably at the edge of the seat.
The seat belt crosses his shoulder between his neck and his arm.
The lap belt sits low on his hips, touching his thighs.
Your child can stay seated like this for the entire car trip.