Puberty is a mine field of emotional and body changes in a young boy.  Many boys become embarrassed when they discover their bodies are changing from child to adult. Many others are excited at the prospect.  Understanding the changes that happen during puberty in boys can help ease some of the anxiety and embarrassment.

 During puberty boys grow faster than at any other time in their lives. They may grow up to five inches in one year.  The shape of the body changes; the shoulders become broader, the hips narrower and muscles and strength increases.  Many boys seem to change overnight, but puberty lasts months or even a few years.  Puberty may happen as young as ten or as old as fifteen with the average age being twelve years.

 The Growth Spurt Changes During Puberty

 Most boys start a growth spurt after their genitals have begun to develop, usually around the ages of 13 or 14 years.  By age fourteen, boys usually have reached 91.5 percent of their adult height.  The bones in the feet grow faster than other bones, especially the backbone; thus many boys will have large feet in relation to their height. The feet will grow to adult size before boys reach their adult height.  Arms and legs also grow faster than the backbone and this may give the “gangly” look to the body.

 As the shoulders broaden, the hips become narrower in comparison. Muscles begin to develop, especially in the upper arms, calves and thighs.  The increase in muscle increases the boy’s body strength.

 These changes can bring about many emotions for boys. Because the rate of change is different for each boy, many go through periods of time when they are either behind or ahead of their peers in regards to body changes and growth.  This can cause some emotional trauma for some boys.  Some boys may desire to be taller or more muscular.  While height cannot be increased, once puberty is over the muscular frame of boys can be increased with the correct exercise and diet plan.

 Body Changes During Puberty

 For most boys the first change that takes place during puberty is the sex organs grow larger. The sex organs are the penis, the scrotum and the testicles.  As puberty continues, these organs continue to grow.   Some boys will start to grow pubic hair as a first sign of puberty, but for most boys, the genitals grow first.  As the scrotal sac grows, it begins to get longer and hang lower.  The skin of the genitals begins to have a different texture and becomes a deeper color. In fair-haired boys, the skin is often reddish and in dark-haired boys, the skin deepens in color.

 The size of the penis also increases during puberty. It becomes longer and wider.  During this time, the testicles are between seven and sixteen milliliters in volume. Usually one testicle hangs lower than the other.  One may be larger than the other.  This is normal at puberty. Once boys have fully grown, there is usually only slight or no difference in the size of the two testicles.

 As puberty continues, the scrotum and penis continue to grow. At the fully grown or adult stage of puberty, the testicles are generally about 1 ¾ inches long and between 16 and 27 milliliters in volume.   The penis is between 3 ¼ and 4 ¼ inches long.  When the penis is erect, it gets temporarily longer; the average length is 6 ¼ inches.  The smaller a penis is when it is soft or flaccid, the more inches it tends to gain when erect.  An erect penis is caused when the blood passageways in the spongy tissue inside the penis fill with blood.  It can happen quickly or slowly and gradually and can be of different degrees of firmness.

 Many boys are concerned about the size of the genitals, especially when they are in the locker room for gym class or sports.  Boys who are developing at a slower rate are often subject to teasing and bullying, while those who are developing at a faster than average rate may be teased, but are more likely to be admired.   Often the teasing is based on myths that are believed; for example, the strength or “manliness” of a boy depends on the size of his penis.

 During puberty, boys start making sperm in the testicles.  In order to make sperm, the testicles have to be at exactly the right temperature. This is why they hang outside of the body.  In cold weather or a cold pool, the scrotum tightens up and draws closer to the body for warmth; in hot weather, they relax and hang lower, further away from the body to stay cool.   As the muscles push sperm along to the penis, it is zapped by a shot of semen which is rich with sugar and vitamins.  The semen gives the sperm energy to continue the journey on its own.  The prostrate gland adds other fluid to the semen.

 When a boy ejaculates, the muscles around the prostrate gland and in the penis and surrounding area force the sperm and semen into the urethra.  They are propelled along and spurt out of the tip of the penis, usually in three to four spurts.   The muscles may have six to fifteen spasms after the spurts.  The feeling of the muscles contracting and the semen spurting out is called an orgasm.   This will feel different to different people.  During this time the penis is firm and erect.  After the ejaculation, the penis relaxes and becomes soft and flaccid.

 Boys can have erections for all sorts of reasons. They do not have to be thinking “sexy” thoughts, nor do the genitals have to be touched or rubbed; even babies have erections from time to time.  Sometimes an erection can be spontaneous.  Most boys experience more erections once they have started puberty.

 An erection may go away by itself, or it will go away after the boy ejaculates.  Sometimes boys ejaculate while they are sleeping.  A common term for this is called “wet dreams.”  Although grown men can have wet dreams, it is much more common when boys are going through puberty.  Many boys have their first ejaculation during a wet dream.   The dream does not have to be sexual in nature for a boy to have an ejaculation.

 Facial and Body Hair Changes in Boys in Puberty

 As the brain increases its hormones, it signals other glands to increase their hormone levels. In boys, the testicles produce testosterone which is responsible for the growth of pubic hair as well as most of the other changes in the boy’s body.  Body hair increases its growth on the legs, thighs, and arms.  During puberty some boys will start to grow chest hair and some boys also start to grow hair on their shoulders and backs and/or on the backs of their hands. The amount of hair varies for each boy.  The amount of hair growth has nothing to do with testosterone—it only starts the hair growth.   The amount of hair is determined by genetics and ethnicity.

 Facial hair starts to grow during puberty.  The first hairs don’t usually show until the sex organs have almost fully developed; the average age is between 14 and 16 years. Some boys of course will start to see some facial hair earlier and some not until they are 19 or 20 years old.

 Usually the first facial hairs appear on the outer corners of the upper lip and fill inwards to the middle of the lips.  About the same time as the mustache is filling in, hairs begin to grow on the upper cheek and just below the center of the lower lip.  Sideburns may also start growing in at this time.

 As boys mature, the hair becomes thicker and darker.  The mustache and beard may not necessarily be the color of the hair on the head.   Facial hair, as with all the other changes, grow at different rates on boys, so some boys may grow full beards and mustaches at the age of 18 while others may not until they are well into their twenties.

 Shaving beards and mustaches as well as sideburns is a personal choice, but for many boys, shaving for the first time is a rite of passage.  For most boys at the same time as the facial hair starts to grow, hair under the arms begins to grow. 

 When pubic hair starts to grow, it may start as pimple-like bumps around the base of the penis and on the scrotum.   These bumps are hairs trying to push through the skin. By about fourteen years of age, most boys have quite a bit of pubic hair.  As boys develop the hair becomes curlier, coarser, and darker. It grows around the base of the penis and sometimes on the scrotum, outward towards the thighs and upwards towards the belly button. 

 Most of the pubic hair is developed by the end of puberty, but it may continue to grow until a boy reaches the age of twenty.  The amount of hair varies and tends to be influenced by genetics.  Boys often take after their fathers in regards to the amount of hair grown.   Other little bumps that appear on the genitals are oil and sweat glands.

 Sweating and Pimples During Puberty in Boys

 Boys may also notice that during this time they are sweating more and the sweat has a more adult odor.  Other areas of the body also start to perspire more and may also take on a more adult odor.  This is due to the hormone testosterone.

 At the same time the sweat glands become more active, so do the oil glands.  The oil glands in the genital area can make the skin of the genitals feel somewhat moist.  The oil glands in the scalp may increase production making the hair oily or greasy and requiring more frequent shampooing.

 Skin problems can erupt as the skin becomes oilier. The amount of oil the glands produce is different in each boy.  Many boys will experience pimples, where the pores of the oil glands become clogged with oil.  Some boys may experience a more severe case of pimples called acne. Acne can cause pitting or scarring of the skin. 

 Some boys develop stretch marks which are purplish or white lines on the skin. This happens when the growth rate is too fast for the skin and the skin is stretch to the point that it loses its elasticity.  Many times the marks will fade with time, but sometimes they do not fade completely.

Changes in the Breast and the Voice

 While it is well known that girls’ breasts change during puberty, most people do not realize that the breasts of boys change as well.  The ring of colored flesh around the nipple, called the areola, gets darker and wider. The nipples may become slightly larger.  The breasts may become tender or sore and underneath the nipples, some boys may experience a small buttonlike bump.  Eventually the bumps and the soreness go away.  Many boys, at least half, experience some swelling of the breasts during puberty.  This swelling can last from 12 to 18 months.

 Testosterone causes the larynx of boys to grow larger.  The vocal cords become thicker and longer and this causes the tone of the voice to change.  This usually happens around the ages of 14 or 15 years.  Some boys do not notice the change until others tell them their voice sounds different.  For other boys, the throat may become sore and scratchy for a few weeks; the change can be sudden and noticeable.  Some boys are embarrassed when their voice changes or “cracks” as they feel out of control and the cracking can cause the voice to sound high and squeaky.

 With all of these changes to the body, it is not unusual for boys to be embarrassed when first experiencing a change.  Boys in puberty do not have to be embarrassing if they know more about what is happening to them.   Understanding their bodies and learning that what they are experiencing is perfectly normal can help boys in puberty navigate the minefield of those chaotic years.



Madaras, Lynda & Saavedra, Dane. The What’s Happening to My Body? Book for Boys. New York: Newmarket Press, 1984.


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