It can be hard to tell exactly when puberty will start in boys. The changes happen slowly over time, not all at once. Every boy is different, but here are the average ages for common changes:

• Puberty starts: Around 9-14 years
• First change: Testicles start to get bigger
• Penis growth: Starts about 1 year after the testicles grow
• Pubic hair appears: Around 13 years
• Underarm hair, facial hair, deeper voice and acne: Around 15 years
• Wet dreams (nocturnal emissions): Around 14 years

First signs

• The first sign of puberty in boys is when the scrotum and testicles get bigger. At this time, the penis does not grow yet.
• Next, as the testicles and scrotum keep growing, the penis starts to get longer.
• After that, the penis grows in both length and width.

Pubic hair growth

• At first, soft, thin hair grows in a small area around the genitals.
• The hair then becomes darker, thicker and coarser.
• Over time, the hair starts to look like adult pubic hair, but in a smaller area.
• It may spread to the inner thighs or up to the stomach.

Learn more about the male anatomy

• Body size increases: Hands, feet, arms and legs may grow faster than the rest of the body. This can make boys feel a little clumsy for a while.
• Breast swelling: Some boys get slight swelling in their chest area during puberty. This is caused by hormones and usually goes away. Talk to your child’s doctor if you are worried.
• Voice changes: The voice gets deeper. It may crack or break sometimes, but this is normal and will get better with time.
• Hair growth: Hair will grow around the genitals, under the arms, on the face and legs.
• Oily skin and sweating: Hormones can make skin oilier and cause more sweating. Daily washing helps. Acne may appear, which is normal.
• Erections: The penis may become hard (erect), sometimes from sexual thoughts or even for no reason. This is normal.
• Ejaculation and sperm: The body starts making sperm. Semen (fluid with sperm) may be released during an erection. This is called ejaculation.
• Wet dreams: Sometimes ejaculation happens during sleep. This is called a nocturnal emission or wet dream. It’s completely normal and will happen less often over time.

Children’s Wisconsin has many resources to help you and your teen through the changes of growing up:

Talking about it: Adolescent medicine specialists in our Teen Health Clinic can help answer questions and clear up confusion or fear about growing up.

Learn about being a tween: As changes begin, it helps to know what’s happening, when to expect it and why it matters.

Safer teen driving: It’s more than just learning the rules. Parents can help their teens build safe driving habits with helpful tips and guidance.

What Does My Teen Understand?

The teen years bring big changes. These are not just in the body, but also in how a teen thinks and feels.

How Teens Think

As they grow:

• They think in deeper and more complex ways.
• They care about things like philosophy, politics or social issues.
• They start to make long-term plans and set goals.
• They may start to compare themselves to others their age.

Relationships and Feelings

As teens try to become more independent, you may notice changes in how they act with others:

• They may want more independence from parents.
• Friends and fitting in becomes very important.
• Peer pressure may play a bigger role.
• They may fall in love.
• They might even be in a serious relationship.

Physical Exams

• A physical exam helps keep you healthy and should be done every year.
• Teens often need physicals before joining sports.
• The doctor may check your teen’s:
• Eyes, ears, nose, throat and mouth
• Abdomen (stomach area), back, legs and arms
• Thyroid (a gland in your neck)
• Genitals (penis and testicles)
• They may also screen for:
• High blood pressure
• Scoliosis (curved spine)
• Obesity (being overweight)