The 5 Stages of Puberty in Boys

How Your Son Develops Into a Young Man

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A boy goes through many important changes during puberty. His body beefs up, his voice cracks as it changes, he becomes stronger, and he begins to mature sexually.

Before you know it, your little boy has become a young man. There are five stages of puberty that boys go through, but keep in mind that the age at which each boy goes through them can vary widely.

Puberty changes in boys
 Illustration by JR Bee, Verywell

Signs of Puberty in Boys

Boys mature a little slower than girls. For boys, puberty begins at age 11 on average, although starting as early as age 9 or as late as age 14 is still considered normal.

Some boys mature faster than their peers, and some physical changes may be more gradual than others.

A number of these physical changes are very personal. As a parent, you may not notice them, but your son will. Some of these may be embarrassing experiences for him and he will likely keep much of this private.

Body Shape

Externally, you may notice your son's body begin to grow, but just before that happens, he may put on a little weight and look like he's all arms and legs. Next comes a growth spurt in height, often around the age of 13.

His shoulders will broaden and his muscles will develop more definition too. He will become noticeably stronger and can take advantage of that by beginning a regular workout routine.

Sweating, Hair, and Acne

Personal hygiene is probably one of the biggest changes for young boys. It may have been hard to get him to wash his hands or take a shower, but now he will need to pay attention to these things as he starts to sweat more and develop body odor.

He may soon come to you and ask about shaving the peach fuzz from his face or ask about antiperspirants. His hormones will produce more oil on his skin and he may be prone to acne breakouts.

This is the perfect time to introduce him to good skin care routines.

Penis and Testicle Growth

The first sign of puberty actually begins with the growth of your son's testicles and scrotum, which will more than double in volume. His penis and testicles will begin to grow as he enters puberty too, as will his pubic hair.

The penis begins by growing in length, followed by width. You can find more details on this growth in the Tanner stages section below. Around one-third of boys have tiny pearly bumps, called papules, on their penises. These bumps look like pimples and are normal and harmless, though they are permanent.

Nocturnal Emissions and Erections

As your son develops, he may begin to have nocturnal emissions, or "wet dreams," in which he ejaculates at night. This can occur with or without a sexual dream and is completely normal.

Talking to your son about nocturnal emissions before they happen is helpful so he knows what to expect and that he hasn't accidentally wet the bed. Let him know that it's just another part of puberty and that it'll go away in time.

Involuntary erections are another big part of male puberty and they can occur at any time, for absolutely no reason at all.

Explain to your son that this may happen for a while, and he will likely have little control over it, but it will get better as he gets older.

Voice Change

Your son's voice will change around the time that his growth spurt has begun to slow down a bit. This occurs because his vocal chords and voice box (larynx) gain mass too. Before his voice changes completely, it may crack and soar, going from high to low quickly. This can be embarrassing for him, so be mindful of this.

Breast Growth

When your son is first in puberty, his breast tissue may swell a bit for a year or two as some of his hormones change into estrogen. For the majority of boys, this is temporary and not excessive, though, in some boys, it can be more obvious, especially if they're overweight.

If your son's breast area seems excessively swollen or the swelling happens before puberty or later in puberty, see your healthcare provider. There could be a medical problem that's causing this swelling rather than hormones.

Mood Swings

Like girls, boys can also have mood swings thanks to the hormonal, physical, and emotional changes they're experiencing. Be patient and understanding; this, too, shall pass.

Tanner Stages of Sexual Development

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 if it's expected for his age. The Tanner stages, along with approximate age ranges, include:

  • Sexual Maturity Rating 1: (The prepuberty stage) The testes are small and the phallus (penis) is child-like. There is no pubic hair.
  • Sexual Maturity Rating 2: (From 10 years old to 15 years old) The testicles grow in volume and size. The penis has no to slight enlargement. The 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 16 years old) The testes continue to grow in volume and size. The penis becomes longer. The scrotum continues to enlarge. Pubic hairs become darker and curlier and more of them appear.
  • Sexual Maturity Rating 4: (From 12 years old to 17 years old) The testicles continue to grow. The penis continues to grow in length and now becomes thicker. The scrotum grows larger and also darkens. Pubic hair is coarse, thicker, and curly like adult hair, though there are fewer hairs than an adult has.
  • Sexual Maturity Rating 5: The testicles are of an adult size (greater than 20 ml in volume). The scrotum and penis are of adult size and form. The pubic hair is of normal adult distribution and volume.

Talking to Your Son

Your little boy is growing up and this also means that he may open up to you less often. It's common for teenage boys to become less talkative and withdraw from their parents. Keep the lines of communication open and talk to your son about the changes he's experiencing.

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

Delayed Puberty

If your son hasn't started puberty by the age of 14, which means that his testicles and penis haven't started to grow yet, this is considered delayed puberty. The most common cause is called constitutional delayed puberty. Most boys who are constitutionally delayed are totally healthy and will go through puberty eventually.

More than two-thirds of boys inherit this from one or both of their parents who also started puberty late. In boys, this can be defined as having no increase in testicle size by the age of 14 years old or continuing undergo puberty for more than five years after the start.

In girls, delayed puberty is starting menstruation after the age of 16 years. The majority of boys who are constitutionally delayed are also short compared to other boys their age, but this is just because they haven't had their growth spurt yet.

If your son has a chronic illness like sickle cell disease, inflammatory bowel disease, or cystic fibrosis, puberty may also begin later than normal.

A small number of boys have a condition called isolated gonadotropin deficiency (IGD), which means that they don't produce adequate amounts of the hormones LH and FSH. This condition typically begins at birth and is typically treated with testosterone injections.

An even smaller number of boys have something going on with their testicles that's causing puberty to be delayed. Testosterone is the main treatment for issues of this sort.

A Word From Verywell

If you have questions or concerns about how your son is progressing through puberty, talk to his healthcare provider. Your doctor can determine if your teen is growing and developing as expected and help you understand the biology that's at work.

In the case of suspected delayed puberty, it's possible that your son's penis and testicles have gradually started to enlarge and he just hasn't noticed. Your doctor can tell with a physical exam and can run some tests on your son's hormones to see if there are any problems.

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14 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Nemours KidsHealth. Boys and Puberty.

  2. Marceau K, Ram N, Houts RM, Grimm KJ, Susman EJ. Individual differences in boys' and girls' timing and tempo of puberty: modeling development with nonlinear growth modelsDev Psychol. 2011;47(5):1389–1409. doi:10.1037/a0023838

  3. Rogol AD, Clark PA, Roemmich JN. Growth and pubertal development in children and adolescents: effects of diet and physical activity. Am J Clin Nutr. 2000;72(2 Suppl):521S-8S. doi:10.1093/ajcn/72.2.521S

  4. Kelly A, Winer KK, Kalkwarf H, et al. Age-based reference ranges for annual height velocity in US childrenJ Clin Endocrinol Metab. 2014;99(6):2104–2112. doi:10.1210/jc.2013-4455

  5. Schoenau E. Bone mass increase in puberty: what makes it happen?. Horm Res. 2006;65 Suppl 2:2-10. doi:10.1159/000091748

  6. Tomova A, Deepinder F, Robeva R, Lalabonova H, Kumanov P, Agarwal A. Growth and Development of Male External Genitalia: A Cross-sectional Study of 6200 Males Aged 0 to 19 YearsArch Pediatr Adolesc Med.2010;164(12):1152–1157. doi:10.1001/archpediatrics.2010.223

  7. Hall A. Pearly Penile Papules. In: Atlas of Male Genital Dermatology. Springer, 2019. doi:10.1007/978-3-319-99750-6_6

  8. Lauridsen LL, Arendt LH, Støvring H, Olsen J, Ramlau-Hansen CH. Is age at puberty associated with semen quality and reproductive hormones in young adult life?Asian J Androl. 2017;19(6):625–632. doi:10.4103/1008-682X.190328

  9. Hari Kumar KV, Garg A, Ajai Chandra NS, Singh SP, Datta R. Voice and endocrinologyIndian J Endocrinol Metab. 2016;20(5):590–594. doi:10.4103/2230-8210.190523

  10. Lemaine V, Cayci C, Simmons PS, Petty P. Gynecomastia in adolescent malesSemin Plast Surg. 2013;27(1):56–61. doi:10.1055/s-0033-1347166

  11. Smith SS. The influence of stress at puberty on mood and learning: role of the α4βδ GABAA receptorNeuroscience. 2013;249:192–213. doi:10.1016/j.neuroscience.2012.09.065

  12. World Health Organization. Antiretroviral Therapy for HIV Infection in Infants and Children: Towards Universal Access: Recommendations for a Public Health Approach: 2010 Revision.

  13. Bozzola M, Bozzola E, Montalbano C, Stamati FA, Ferrara P, Villani A. Delayed puberty versus hypogonadism: a challenge for the pediatricianAnn Pediatr Endocrinol Metab. 2018;23(2):57–61. doi:10.6065/apem.2018.23.2.57

  14. Howard SR. The Genetic Basis of Delayed PubertyFront Endocrinol (Lausanne). 2019;10:423. doi:10.3389/fendo.2019.00423

Additional Reading
  • American Academy of Pediatrics and Pediatric Endocrine Society. Delayed Puberty in Boys: Information for Parents.

  • American Academy of Pediatrics and Pediatric Endocrine Society. Physical Development in Boys: What to Expect.

  • Kliegman, RM. et. al. Nelson Textbook of Pediatrics. Elsevier; 2016.

  • Neinstein LS, Katzman DK. Neinsteins Adolescent and Young Adult Health Care: a Practical Guide. Philadelphia: Wolters Kluwer; 2016.