What are the stages of puberty for boys?

5 Stages: 1 Male hormones become active, but few outside signs of development. 2 Testicles/scrotum enlarge, but not penis. Increase height/change in body shape. 3 Penis lengthens, but not much in width. Testicles/scrotum still growing. Pubic hair starts. Voice deepens. 4 Penis widens/lengthens. Testicles/scrotum still growing. Pubic hair adult form. 1st ejaculates. Axillary/facial hair. 5 Adult appearance.

Tanner 1 to 5: Tanner1: infantile genititals. 2: growth of the testicles and early elevation of testosterone. Scattered pubic hair. 3: growth of the penis and more pubic hair. 4: penis and testicles approaching adult size, pubic hair now a full triangle. 5: pubic hair extends to thighs and lower abdomen, and facial hair is present. Puberty usually starts at age 12 and continues for 3-4 years.