The 5 Stages of Puberty in Boys

A male child goes through many important changes during puberty. 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 that children assigned males at birth go through. Puberty tends to begin later for males than females, and typically starts between age 9 and 14. However, keep in mind that the timing of when each stage starts and ends varies widely, so the age at which your child goes through them can be hard to predict. Learn more about the stages of puberty for boys.

 Illustration by JR Bee, Verywell

Tanner Stages of Sexual Development

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 what stage your tween or teen is at and if it’s expected for their 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 or 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 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.

Signs of Puberty in Boys

Males mature a little slower than females. 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 likely will. Some of these may be embarrassing experiences for them and they will likely keep much of this private.

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 will 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 will need to pay more attention to these things as they start to sweat more and develop body odor.

They may soon come to you and ask about shaving the peach fuzz from his face or ask about antiperspirants. Their hormones will 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 they 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.

Breast Growth

When your child is first in 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 healthcare 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.

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.

Talking to Your Child

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 talk to your tween or teen about 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.

Delayed Puberty

If your child 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 males who are constitutionally delayed are totally 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 years old or continuing to undergo puberty for more than five years after the start.

In females, delayed puberty is starting menstruation after the age of 16 years. 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.

If your child 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 male children 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 male children 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 child is progressing through puberty, talk to their healthcare provider. Their doctor can determine if your tween or 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 child’s penis and testicles have gradually started to enlarge and they just haven’t noticed. Your doctor can tell with a physical exam and can run some tests on your child’s hormones to see if there are any problems.