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The stages of puberty in boys

As a parent with a son who is on the cusp of puberty, awareness of the stages of puberty in boys is a handy thing to know. Why? Because by knowing what the stages of puberty in boys are, you can at least be prepared for what changes will be happening to your son. And prepare your son by talking about them before they even happen. Especially when it comes to things like wet dreams!

When we look at breaking puberty up into stages of development, we are often talking about the Tanner Scale. A British paediatric endocrinologist, James Tanner,  developed the Tanner Scale in the mid-1900’s to measure the stages of sexual development during puberty.

The Tanner Scale is still used today. Although puberty starts earlier in kids today, the sequence of changes that happen in boys is unchanged.

And don’t forget that the timing of when these changes will happen to your son vary. Some boys can be earlier or later than others.

So what are the stages of puberty in boys?

PS I have tried to keep this post jargon-free but I have used the correct names for the private parts of the body ie the genitals. This article talks about the importance of using the correct terms when talking to kids about their private parts of their body, and it is has a download where they are all labelled for you.

You’ll find more information about puberty in my Puberty 101 page.

Stage 1

(approximately between the ages of 9 and 12)

So what can you expect with the first of the stages of puberty in boys?

The first changes that will happen to your son are hidden as they are happening deep inside his body. The body will start to release hormones that will trigger the changes to start happening. The main hormone for boys is testosterone. It will begin to surge in your son’s body, causing his testicles to grow and make sperm, but no changes can yet be seen outside his body.

No changes can yet be seen outside his body, other than some growth of the scrotum and testicles. Some boys may have a growth spurt, and some may start to grow very fine hairs in the pubic area.

Stage 2

(approximately between 9 and 14)

So what can you expect with the second of the stages of puberty in boys?

Your son’s testicles will continue to slowly grow, with one testicle now beginning to hang lower than the other. His scrotum will also hang lower, becoming darker in colour, thinner and less smooth. His penis will remain unchanged. It may grow slightly larger, but usually there is little or no change at all. He may start to have erections more frequently, but he still isn’t ejaculating.

Fine hair may begin to grow at the base of the penis and scrotum. These first hairs are usually long, slightly pigmented (colored) and straight or slightly curly. It is normal for some boys not to grow hair just yet.

Your son will start to grow taller and the shape of his body will begin to change. Before he grows taller, his feet and hands will usually have a growth spurt of their own. Your son will also gain weight as he starts to develop muscle, and as his bones grow bigger.

Stage 3

(approximately between 11 and 16)

So what can you expect with the third of the stages of puberty in boys?

Your son’s testicles and scrotum will continue to grow. Sperm production may begin for some, but not all, boys, i.e. ejaculation. Boys usually discover this during masturbation, or they might wake up in the morning with wet pants after a wet dream (nocturnal emission). His penis will start to grow. It will grow longer, rather than wider. Erections will be a lot more common than before, often at the wrong time, or in the wrong place.

Some boys may only now be starting to develop pubic hair. It will become darker, thicker and curlier, and start to cover a much wider area. Hair will continue to grow on his legs and underarms.

It can be common for boys to experience short-term swelling and tenderness around the nipples. As their shoulders grow wider, this breast tissue will flatten, usually disappearing within one or two years.

Your son’s body will still be growing, and gaining weight and height. Sweat and oil glands will become more active, which can result in acne. Body odor is here to stay. His voice will begin to crack as the voice box gets larger.

Stage 4

(approximately from 11 to 17)

So what can you expect with the fourth of the stages of puberty in boys?

Your son’s testicles and scrotum will continue to grow, with the skin continuing to darken. Boys will now begin to produce sperm, which means that wet dreams (nocturnal emissions) may start to happen, and they will ejaculate with masturbation and sexual arousal. Not all boys will have wet dreams (either is normal).

His penis will become thicker and longer. Pubic hair continues to grow as well as on his legs and underarms. Facial hair will start to grow on his face, usually on the upper lip, chin and near the ears.

Your son’s skin may become oily, especially around the chin, nose, forehead, chest and/or back. Some boys may develop acne or pimples. His hair is also more likely to become oily too. His voice will continue to crack at times and deepen.

Your son will keep on gaining weight and growing taller.

Stage 5

(approximately between 14 and 18)

So what can you expect with the fifth and last of the stages of puberty in boys?

This is the last stage of changes. Your son will now reach his full height and will look like a young adult. His pubic hair will now cover his groin, and possibly even his inner thighs. His genitals will now be fully grown and will look the same as those of an adult man. Your son will now need to shave, as his facial hair continues to grow. Some boys will begin to grow chest hair.

Puberty resources

It is easy to get overwhelmed at the thought of talking about the stages of puberty in boys. A lot of parents feel the same way.

The book, Boy Puberty: How to talk about puberty and sex with your tween boy, was written to help parents to get started with talking about puberty. It tells parents everything they need to discuss and how to start talking about it. You can get a copy of it at Sex Ed Rescue.

If you are looking for more blogposts on puberty, you can find that here.

There are also many books on puberty that will help you to talk about the stages of puberty in boys.


  • Adolescence and Puberty. Edited by John Bancroft and June Machover Reinisch. 1990. Oxford University Press. New York.
  • Gender Differences at Puberty. Edited by Chris Haywood. 2003. Cambridge University Press. Cambridge.
  • Handbook of Child and Adolescent Sexuality: Developmental and Forensic Psychology. Edited by Daniel S. Bromberg and William T. O’Donohue. 2013. Elsevier. Academic Press. Oxford.
  • Puberty: Physiology and Abnormalities by Philip Kumanov and Ashok Agarwal. 2016. Springer International Publishing. Switzerland.

About the Author Cath Hakanson

I'm Cath, a sex educator living in Australia with my husband and 2 kids. I help parents to talk about sex (with less cringe and more confidence) and to empower their child to make smart sexual decisions. You can join my online parent support group here and visit my shop for helpful resources.

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