when do boys stop growing?
Male Growth Patterns. Boys generally hit their growth spurt about two years after girls, according to KidsHealth.org. Most boys grow most quickly between ages 12 and 15 and stop growing by age 16, but this depends on when they reach puberty. Boys usually continue developing muscles and gaining weight after they stop growing taller. The average adult male in the United States is about 69 inches tall, according to the CDC.