1
Normal Age Range: 9-12, Average: about 10 Male hormones are becoming active, but there are hardly, if any, outside signs of development. Testicles are maturing, and some boys start a period of rapid growth late in this stage.
2
Normal Age Range: 9-15, Average: 12-13 Testicles and scrotum begin to enlarge, but penis size doesn't increase much. Very little, if any, pubic hair at the base of the penis. Increase in height and change in body shape.
3
Normal Age Range: 11-16, Average: 13-14 Penis starts to grow in length, but not much in width. Testicles and scrotum still growing. Pubic hair starts to get darker and coarser and is spreading towards the legs. Height growth continues and body/face shape look more adult. Voice begins to deepen (and crack). Some hair around the anus grows.
4
Normal Age Range: 11-17, Average: 14-15 Penis width increases, as well as length. Testicles and scrotum still growing. Pubic hair begins to take adult texture, although covers a smaller area. Most boys have first ejaculations. Underarm hair develops. Facial hair increases on chin and upper lip. Voice gets deeper and skin gets more oily.
5
Normal Age Range: 14-18, Average: around 16 Nearing full adult height and physique. Pubic hair and genitals have adult appearance. Facial hair grows more completely and shaving may begin now or soon.
During the late teens and early twenties, some men grow a bit more and develop more body hair, especially chest hair.
