The 5 Stages of Puberty in Boys

Puberty can start anytime between ages 9 and 14, but changes follow a set pattern. Learn more about what to expect.

Medically reviewed by Teja Dyamenahalli, MD, MPH, FAAP

At the first sign of puberty in males, you'll notice that they're beginning to go through many important changes that will help them transition to adulthood. Their body gets bigger and stronger, their voice cracks as it changes, they become more muscular, and they begin to mature sexually.

While the entire process takes several years, there are five stages of puberty for children assigned males at birth. Puberty tends to begin later for males than females, and typically starts between age 9 and 14—though the timing varies widely. Learn more about the stages of puberty for boys and what to do if you suspect if they're delayed.

<p>Illustration by JR Bee</p>

Illustration by JR Bee

Tanner Stages of Sexual Development

Tweens and teens who were assigned male at birth will develop physically in certain stages, often called Tanner stages. Your pediatrician or family health care provider can determine which stage your child is experiencing, and whether it's expected for their age. Here is a general guideline of what the Tanner stages include:

  • Sexual Maturity Rating 1: The testes are small and the phallus (penis) is child-like. There is no pubic hair.

  • Sexual Maturity Rating 2: The testicles grow in volume and size. The penis has slight enlargement or none at all. The scrotum becomes reddened, thinner, and larger. A few pubic hairs become visible but are downy-like.

  • Sexual Maturity Rating 3: The testes continue to grow in volume and size. The penis becomes longer and the scrotum continues to enlarge. Pubic hairs become darker and curlier and more of them appear.

  • Sexual Maturity Rating 4: The testicles continue to grow. The penis also continues to grow in length and 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 adult size (greater than 20 milliliters in volume). The scrotum and penis are of adult size and form. The pubic hair is of normal adult distribution and volume.

Signs of Puberty in Boys

For people assigned male at birth, 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 males 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 child will. Some of these may be embarrassing experiences for them and they'll likely keep much of this private. Here's what to expect.

Body shape

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

Their shoulders will broaden and their muscles will develop more definition, too. They'll become noticeably stronger and can take advantage of that by beginning a regular workout routine if desired.

Sweating, hair, and acne

Personal hygiene is probably one of the biggest changes for young males. Pre-puberty, it may have been hard to get them to wash their hands or take a shower, but now they'll need to pay more attention to these things as they start to sweat more and develop body odor.

They may ask about antiperspirants or shaving their peach fuzz. Their hormones will also produce more oil on their skin, and they may be prone to acne breakouts. Puberty is the perfect time to introduce them 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. Their penis and testicles will begin to grow as they enter puberty, too, as will their pubic hair.

The penis begins by growing in length, followed by width. Around one-third of males 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 tween or teen develops, they may begin to have nocturnal emissions, or "wet dreams," in which they ejaculate at night while sleeping. This can occur with or without a sexual dream and is completely normal.

Talking to your child about nocturnal emissions before they happen is helpful so they know what to expect and that they didn't accidentally wet the bed. Let them 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 can occur at any time, for absolutely no reason at all. Explain to your son that this may happen for a while, and they will likely have little control over it, but they will gain greater control as they get older.

Voice change

Your child's voice will change around the time that their growth spurt has begun to slow down a bit. This occurs because their vocal cords and voice box (larynx) gain mass, too. Before their voice changes completely, it may crack and soar, going from high to low quickly. This can be embarrassing for them, so be mindful of this and try not to call attention to it.

Breast growth

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

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

Mood swings

Boys often have mood swings thanks to the hormonal, physical, and emotional changes they're experiencing. Be patient and understanding. This, too, shall pass.

Puberty and Gender Identity

Note that puberty can be more difficult or confusing for children who are questioning their gender identity. Offering unconditional acceptance, support, and counseling, if needed, can help to ease their discomfort and boost their confidence and self-esteem.

Related: When Do Boys Stop Growing?

Talking to Your Child About Puberty

Your little boy is growing up, and this also means that they may open up to you less often. It's common for teenagers to become less talkative and withdraw from their parents. Keep the lines of communication open and discuss the changes they're experiencing.

Stay connected to their interests and talk to them about hobbies, sports, school, or whatever they enjoy. This will help them feel comfortable about coming to you when they need to talk about something important.

Is Your Child Experiencing Delayed Puberty?

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

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

The majority of males who are constitutionally delayed are also short compared to other males their age. But this is just because they haven't had their growth spurt yet.

Other potential causes of delayed puberty in males include:

  • Chronic illnesses like sickle cell disease, inflammatory bowel disease, or cystic fibrosis

  • A condition called isolated gonadotropin deficiency (IGD), which means that they don't produce adequate amounts of the hormones LH and FSH

  • An endocrine disorder, such as panhypopituitarism, that is impacting their testicles

  • Nutritional deficiencies, malnutrition, or eating disorders

Related: How Do I Help My Tween Cope With Puberty Problems?

Key Takeaway

If you have questions or concerns about how your child is progressing through puberty, talk to their health care provider. In the case of suspected delayed puberty, it's possible that your child's penis and testicles have gradually started to enlarge and they just haven't noticed. Their doctor will do a physical exam and run some tests on your child's hormones to see if there are any problems.

Related: Everything Parents Need To Know About Precocious Puberty

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