His Changing Body: The Stages of Puberty in Boys

How Your Son Develops Into a Young Man

Teenage boy exercising with dumb bell
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Boys go through many important changes during puberty. Their body beefs up, their voice cracks, they become stronger and they begin to mature sexually. Teenage boys may not change as significantly as girls, but they do change a lot and before you know it, your boy has become a young man.

Signs of Puberty in Boys

Boys mature a little slower than girls and puberty typically begins around 9-years-old. Some boys will mature faster than their peers and some physical changes may be more gradual than others.

A number of the physical changes are very personal and as a parent you may not notice them, but your son will. His penis and testicles will begin to grow, as will pubic hair.

Soon, he may begin to have sexual thoughts and wet dreams. These may be embarrassing experiences for him and he will likely keep much of this private.

Externally, you may notice your son's body begin to grow. He will get taller, his shoulders will broaden and muscles will develop more definition. He will become noticeably stronger and can take advantage of that by beginning a regular workout routine.

Personal hygiene is probably one of the biggest changes for young boys. Before puberty it may have been hard to get him to wash his hands or take a shower, now he is going to want to pay attention to these things.

He may soon come to you and ask about shaving the peach fuzz from his face or ask about antiperspirants because he is sweating more than usual.

His hormones will also produce more oil on his skin and he is prone to acne breakouts. This is the perfect time to introduce him to good skin care routines.

Talking to Your Son

Your little boy is growing up and this also means that he may open up to you less often. It is common for teenage boys to become less talkative and withdraw from his parents.

Keep the lines of communication open and talk to your son about the changes he's experiencing, but don't leave it at that subject alone!

Stay connected to his interests and talk to him about sports, school or whatever he enjoys. It will help him feel comfortable about coming to you when he does need to talk about something important.

Tanner Stages of Puberty in Boys

Teen boys will develop physically in certain stages, often called Tanner stages. Your pediatrician or family health care provider can determine what stage your teen is at and determine if it is appropriate for his age.

  • Sexual Maturity Rating 1. Prepuberty stage. Testes are small and phallus (penis) is child-like. There is no public hair.
  • Sexual Maturity Rating 2. From 9 years old to 14 years old. Testicles grow in volume and size. Penis has no to slight enlargement. Scrotum becomes reddened, thinner and larger. A few pubic hairs become visible, and they are long, straight and slightly dark.
  • Sexual Maturity Rating 3. From 10 years old to 14 years old. Testes continue to grow in volume and size. Penis becomes longer. Scrotum continues to enlarge. Pubic hairs become darker and curlier and more of them appear.
  • Sexual Maturity Rating 4. From 11 years old to 15 years old. Testicles continue to grow. Penis continues to grow in length and now becomes thicker. Scrotum grows larger and also darkens. Pubic hair is coarse, thicker and curly like adult hair but there are fewer hairs than an adult.
  • Sexual Maturity Rating 5. Testicles at an adult size (greater than 20 ml in volume). Scrotum and penis are adult size and form. Pubic hair is normal adult distribution and volume.

Confusing? Don't worry. If you have questions or concerns about how your teen is experiencing puberty, talk to your teen's health care provider. Your provider can determine if your teen is growing and developing correctly.


Behrman, RE, Kliegman, RM, and Jenson, HB. Nelson Textbook of Pediatrics, 2004.

Neinstein, LS. Adolescent Health Care: A Practical Guide, 2002.

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