What are the weight and height requirements for rear-facing use?

For rear-facing use, children must weigh 2.3 to 18 kg (5 to 40 lbs) and have a height of 48 to 102 cm (19 to 40 in.) with the top of their head at least 25 mm (1 in.) below the top of the child restraint seat back. Once your child exceeds any of these size requirements, they must transition to forward-facing use if possible.