Boys' bodies Q&A

Puberty can be a confusing time because your body and your feelings are changing as you grow up. Here are answers to some of the questions that boys often ask about their bodies. 

At what age do you go through puberty?

Puberty describes all the physical changes that children go through as they grow into adults. Most people start to notice changes at around 11 years old, but there's no right or wrong time to start puberty. It might be sooner or it might be later, and this is normal.
Read more on boys and puberty.

What's the average penis size?

Penis size varies from man to man, in the same way that everyone is a different height, weight and build. Most men's penises are somewhere around 9cm (3.75in) long when they’re not erect, but it’s normal for them to be shorter or longer than this. Some things can make your penis temporarily smaller, such as swimming or being cold.
Most penises are roughly the same size when they’re hard, between about 15 and 18cm (6-7in) long. You can’t make your penis larger or smaller with exercises or medication. Find out more about penis size.

What is circumcision?

Circumcision is an operation to remove the piece of skin (the foreskin) that covers the tip of the penis. In the UK, it's usually done for religious reasons, and is most common in the Jewish and Muslim communities. If you have been circumcised, it's nothing to worry about. It won’t affect your ability to have sex. 
Female genital mutilation (also called female circumcision) is illegal in the UK. It involves cutting off some or all of a girl’s external genitals, such as the labia and clitoris.

I have spots on my penis and it itches. Is this normal?

If you've recently had sex without using a condom you may have picked up a sexually transmitted infection (STI). Visit a sexual health or genitourinary medicine (GUM) clinic, GP, nurse, young people’s clinic or a community contraceptive clinic. Find a sexual health clinic near you.
Lots of boys have normal lumps and bumps on their penis, and spots can also be caused by an allergy or irritation. But if you're worried, seek advice from a doctor or clinic. Medical people see problems like this every day, so there's nothing to be embarrassed about.

Is it normal for my penis to smell fishy and have white bits behind the tip?

This can happen naturally from time to time. To prevent it happening, wash gently behind the foreskin if you have one (men who have been circumcised don’t have a foreskin) when you bath or shower. Use water, or water and a mild soap. Find out more about washing your penis.
If you're washing carefully and the symptoms don't go away, and you've had sex without a condom, you may have an STI. See a doctor, or visit a sexual health or genitourinary medicine (GUM) clinic, young people’s sexual health or a community contraceptive clinic.

What is sperm?

Sperm is produced in the testicles (balls) and released in fluid called semen during sexual activity. Every time a man ejaculates (comes) he can produce more than 100 million sperm. But it only takes one sperm to get a girl pregnant, and that can happen before the boy ejaculates. This is because the fluid that comes out of the tip of his penis before he ejaculates (called pre-ejaculatory fluid) can contain sperm.
If you're having sex with a girl, always use contraception and condoms to prevent both pregnancy and STIs. Talk to your partner about what contraception she's using, and make sure that you use condoms too.
If you’re having sex with a boy, always use condoms to stop yourself getting an STI or passing one on.

Is it normal to get an erection when you wake up in the morning?

Yes, most boys have an erection when they wake up in the morning, and they can get one when they're not expecting it during the day, even when they’re not sexually excited. This is a normal part of sexual development and growing up.

Is it normal for one testicle to hang lower than the other?

Yes, this is normal and nothing to worry about. One theory is that it stops your testicles banging together when you run.

How do I know if I have testicular cancer?

Check your testicles every month by gently rolling them, one at a time, between your thumb and fingers to feel for any unusual lumps or bumps. You’ll feel a hard ridge on the upper back of each ball. This is the epididymis, where sperm is stored, and it’s normal to feel it here.