What is the height and weight for a child to go from an infant seat into a high back booster seat?

Depends. Each restraint system has a sticker on the body that details the ht &weight range for the seat. Kids should rear face until @ least 2y or longer to protect their neck from spinal cord injury. Boosters with improved integrated 5 pt harness are available up to 60-85 lb which remain the best protection in a roll over or t bone crash. You never get to pick your type of crash.