Every boy’s experience of puberty is unique, and there’s a wide range when it comes to the age at which different kids will hit particular milestones, like developing facial hair or a deeper voice. (1) That said, the usual sequence of physical changes in puberty follows a predictable pattern. 

Tanner stages — also known as the Sexual Maturity Rating scale — describe the sorts of body changes you can expect during each phase of development. Check out our guide to learn about some of the common physical changes for boys during puberty and how you can support your child through each stage.‍

Puberty for boys starts around age 11‍

The signs of puberty in boys may begin to be noticeable between the ages of 9 and 14 (2). Some boys start the process earlier, and some later (2). On average, boys begin puberty when they are 11 years old (3). When a boy hits puberty before age 9, this is considered precocious, or early, puberty. If he’s shown no signs of puberty by age 14, he may be experiencing delayed puberty (2). Delayed puberty can sometimes indicate a medical condition. If your son is older than 14 and hasn’t started puberty yet,  checking in with a healthcare provider might help you figure out why puberty is delayed. ‍

Puberty usually lasts around four years‍

Most boys will reach sexual maturity and reach their adult height by the age of 18 (4). Sexual maturity is defined as having fully developed genitals and mature sperm that can fertilize an egg. Depending on when signs of puberty began, some boys may reach physical maturity earlier or later.‍

There are 5 tanner stages of puberty for boys‍

Tanner stages, or the Tanner scale (also known as Sexual Maturity Rating), is a way for healthcare professionals to measure reproductive development in children and adolescents. Although kids of all genders go through predictable stages of puberty, there are some changes that are specific to boys and adolescents with penises. Here’s when you can typically expect each stage to begin (although age varies from person to person because every body is different), what changes to expect, and how to support your child through these transitions. ‍

Tanner stage 1: Before 11 years old or pre-pubescent‍

Changes to expect

• There are no outward physical changes during this stage.
• The pituitary and adrenal glands start producing hormones to prepare the body for puberty. (5; 6)

How to support your child during this stage

Even if your son hasn’t developed any signs of puberty, empowering him with knowledge about the changes he can expect can help him feel more comfortable with his body. Providing medically accurate, age-appropriate information about puberty and sexuality can help to ease the transition.

Boys usually start showing signs of puberty later than girls and may be shorter than many girls in their peer group during this stage (7). You can reassure your child that this is expected and that he will likely catch up within a year or two.‍

Tanner stage 2: 11 years old ‍

‍Changes to expect

• The testicles enlarge, and the skin of the scrotum gets darker and thinner. (5)
• Straight, soft hair appears around the base of the penis. (5)
• A change in body composition during this stage is common, as many boys lose “baby fat,” and start to take on a leaner appearance. (5)
•  Sex hormones like testosterone increase; boys at this stage may be curious about sex and experience erections (sometimes in response to sexual thoughts and sometimes for no reason at all) and nocturnal emissions (wet dreams). (1)
•  Many kids at this age are more interested in spending time with friends than with their parents. (1)

How to support your child during this stage‍

You can help your son develop a healthy relationship with sex and his changing body by answering his questions in a matter-of-fact and judgment-free way and giving him information appropriate to his development.

As puberty begins, your child may feel the need for greater privacy and experience self-consciousness about his body. Give him more space while bathing or changing clothes, and avoid commenting on or teasing him about his changing appearance. (1)‍

Tanner stage 3: Between 12 and 14 years old ‍

Changes to expect

• Many boys experience a dramatic growth spurt during this stage and may gain up to 4 inches of height. (6)
• The testicles and scrotum continue to enlarge. (5)
• The penis will increase in size. (5)
• Pubic hair will become darker and coarser. (5)
• Muscle mass increases. (5)
• The voice begins to deepen and may crack. (5)
• Gynecomastia, the growth of a small amount of breast tissue, is very common during this stage, affecting about half of all boys. (1; 5)
• Kids at this stage often have a growing need for independence and may seem moody or more prone to strong emotions. (1)

How to support your child during this stage‍

Although gynecomastia is totally normal, boys who develop it may experience embarrassment or self-consciousness. You can reassure your son that breast tissue is usually temporary and will likely disappear within a few months to a year.

Making sure that they have a good relationship with a healthcare provider who can answer their questions confidentially can help ensure they have a safe place to get the information they need about their changing bodies and the challenges that come with puberty.‍

Tanner stage 4: Between 14 and 16 years old ‍

Changes to expect

• The penis and testicles continue to increase in size. (5)
• Sperm production often begins during this stage. (3)
• Facial hair may increase during this stage. (5)
• Many boys will start to sweat more and develop body odor during this time. (5)
• Acne may develop on the face, chest, or back. (5)
• Thicker hair grows on the limbs and torso, and under the arms. (5)
• Voice changes continue. (5)

How to support your child during this stage‍

Make sure that your child knows they can turn to you with any questions or concerns they might have. Cultivating a trusting relationship is key to helping your child navigate sexual feelings, relationships, peer pressure, and other common issues faced by boys during puberty.

Encourage your son to take care of his personal hygiene by helping him choose a deodorant and discussing shaving and skincare. Acne can be a big concern for some boys; if your child is experiencing severe acne, check in with a healthcare provider who can help him explore treatment options.‍

Tanner stage 5: Between 16 and 18 years old‍

Changes to expect

• During this stage, boys usually reach their full height.(4)
• Muscle mass increases. (5)
• Some boys at this stage can grow a beard. (5)
• Body hair spreads from the pubic region to the inner thighs and lower belly. (5)
• Some boys start dating or form longer-term relationships. (1)

How to support your child during this stage‍

During this stage, many kids are in the process of forming an independent identity. (1) You can support your child by being open to their perspectives and ideas, giving them space to form their own opinions about important issues, and offering nonjudgmental guidance.

It can be tempting to lecture teens about what you consider proper behavior, or to avoid challenging or potentially awkward subjects like sex and pornography. Research has suggested, however, that kids whose parents speak with them openly and share their values in a nonjudgmental way are more likely to wait longer to have sex and to make safer choices when they do. (8)‍

4 tips for talking to your son about puberty

1. Let him know what to expect. Empowering your son with knowledge about what he might expect during puberty — like wet dreams, involuntary erections, the growth of breast tissue, body odor, acne — can make these changes less worrisome and help him to adjust more quickly to his changing body.‍

2. Stay nonjudgmental. Your child may be more likely to come to you with their questions and concerns if you communicate in a way that emphasizes care and connection and avoids shaming and lecturing. (8)‍

3. Communicate early and often. Don’t limit yourself to a single “talk” where you lay out the facts of puberty and share information about sex and reproduction. Having open-ended conversations throughout your son’s life can help prepare him for each developmental stage and cultivate trust.‍

4. Share resources. Although it’s important for parents to communicate with their kids about puberty, sexuality, and other potentially challenging topics, making sure that your son has other sources of information can be very helpful. Common Sense Media has a list of books about puberty for kids of every age that cover topics including puberty, sexuality, consent, masturbation, gender identity, and more.‍

The bottom line‍

Puberty can be an exciting and challenging time for kids and their parents. Making sure that your son knows he can count on you for support can ease the transition and help him to make healthy choices.