Question: how old for a child to use a booster seat?
Answer: Booster seats Ontario's Highway Traffic Act requires children weighing 18 kg to 36 kg (40 to 80 lb.), standing less than 145 cm (4 ft. 9 in.) tall and who are under the age of 8 to use a booster seat or allows the continued use of a forward-facing seat as long as the car seat manufacturer recommends its use.