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His Changing Body: The Stages of Puberty in Boys


Updated May 20, 2014

Boys and Puberty
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Stages of Puberty in Boys

Boys go through many important changes during puberty. But what does puberty in boys look like? 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.

Tanner Stages of Puberty in Boys

  • 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 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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