Question

When does a girl/boy stop growing?

Answer 1

Girls stop growing at about the age of 16 and guys stop growing from 18 to 21. But it really depends on the person.

Answer 2

Different parts of people never stop growing such as ears and brains. But in terms of height many boys will stop growing around 16-18 but many factors go in to height such as depending on when they started puberty and if being tall is in their genes.
For girls, on the other hand, they continue to grow till their early 20s as many women tend to me smaller than their male counterparts.