Among the key changes is the sexual maturation boys will undergo as The average penis length by age, outlined in Adolescent and Young.
Usually by the end of puberty, a guy's penis has reached its expected size. Puberty usually ends about 4 years after it starts, so this is usually around age 13 –19.
Learn the average penile length by age 16, what to expect as your penis and other hormone-related disorders that affect penis size and male.