You should stop using an infant car seat when your child meets one or more of the following criteria: they exceed the seat's maximum weight limit (typically 30-35 pounds), the top of their head is less than one inch from the top of the car seat shell, or they reach the maximum height limit specified by the manufacturer. These limits are non-negotiable for safety.
The transition isn't just about size. It also coincides with developmental milestones. Most children outgrow their infant seats by height before weight, often between 9 and 18 months. Once your child can sit upright unassisted and has the torso strength for a longer ride, it's a sign they are physically ready for the next stage.
The next step is a convertible car seat, which can be used rear-facing and later forward-facing. The American Academy of Pediatrics (AAP) strongly recommends keeping children rear-facing for as long as possible, ideally until they reach the highest weight or height limit allowed by their convertible seat. Rear-facing is significantly safer, as it cradles the head, neck, and spine in a crash, distributing forces more evenly across the entire shell of the seat.
The following table outlines the typical limits that signal it's time to move on from an infant seat, compared to the subsequent stage.
| Factor | Infant Car Seat Limit | Convertible Car Seat (Rear-Facing) Limit |
|---|
| Weight | 30-35 lbs | 40-50 lbs |
| Height | Varies by model; head within 1" of shell top | Up to 40-49 inches |
| Age (Guideline) | 9-18 months | Up to 2-4 years |
Always prioritize the specific limits on your seat's label over general age guidelines. The safest practice is to maximize the rear-facing position in a convertible seat before even considering turning it forward-facing.
