Question: what is the average size of a one year old boy?
Answer: At one year, boys are around 29 3/4 inches (75.7 cm) and girls average 29 inches (74 cm). The factors that determine height are: Genetics: The height of a child's mother, father, and other family members have the most significant impact on how tall the child will be. Gender: Boys tend to be taller than girls.