According to the world health organization (WHO), the average height for an 11 year old boy is 143 centimeters (56.29 inches). Please see the related links for details.
A 21 -year-old boy? More like a young man. If he is 6ft tall that is 182.88 cm
That is exceptional, your the next Usain Bolt!
The average height for a 9 year old boy is 49inches (4ft1)
average height for 32 month boy
The average height is approximately 5'9" tall.
The average height of an 11 year old boy is 1m 50cm or 5'0"
The average height of a twenty month old boy is 33.1 inches. The average weight for a boy of the same age is 25 lbs.
The average height at the 50th percentile is exactly 4'7''
The average height for a 10 year old Asian boy is... 4ft7 - 4ft8.