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University of Minnesota Extension

Physical development in teens

This fact sheet is part of the Teen talk: a survival guide for parents of teenagers series.

When we hear the word teenager, the first thing that comes to mind is puberty and all the physical changes that teens go through. Teens are developing adult-like physical features and are also becoming sexually mature, which includes developing new feelings about their bodies and relationships. Physical maturation generally occurs before teens mature mentally, socially and emotionally.

Physical changes

The physical changes that indicate the start of puberty start between ages 8-13 for girls (on average around 11) and ages 9-14 for boys (on average around 12). Some of the first physical signs of puberty in girls are breast development, body odor, underarm hair, pubic hair and acne. Menarche, the beginning of menstrual periods, usually begins about two years following the first signs of puberty. Girls may experience a growth spurt in height and overall body shape in the early teen years. Girls will continue to grow, although a little more slowly, until age 17 or 18. Boys might notice pubic hair, a change in their voice, underarm hair, acne and facial hair. Boys often begin their growth spurt in height at age 10 or 11, peaking at around age 14. They finish growing physically at about age 21.

Early or late development

Getting used to a rapidly changing body can lead teens to feel uncomfortable with their new shape and looks. They might also experience physical awkwardness when one part of the body hasn't caught up with the rest. 

Developing off time from when your peers are developing can also make it worse. Early and late maturation has different implications for girls and for boys. When girls and boys develop early:

  • They might start noticing they look different than classmates.
  • They might be treated differently because they look older.
  • They might attract attention from older boys or girls. This is often a bigger issues for girls who develop early. This can result in having to deal with situations beyond their emotional and cognitive abilities.

When boys develop late, the differences between girls and boys may become more noticeable since girls generally develop physically before their male peers. Late development can lead to teasing that results in low self-esteem.

What parents can do

  • Start talking about upcoming biological and physical changes at ages 8 or 9. Some children will become curious earlier and have questions.
  • Tailor discussions about biological and physical changes to your teen's age. 
  • Take your teen's concerns seriously. Listen closely and don't discount his feelings of being different or "something is wrong with me."
  • Avoid comments that will further embarrass your teen. For example, don't point out something about her physical appearance. 
  • Don't mistake physical maturity for overall maturity. It can take time for emotional maturity to catch up to a teen's body.

Related resources

The Teen Years ExplainedClea McNeely, PhD and Jayne Blanchard — This e-book can help both teens and adults to understand developmental changes and tips for how to apply this knowledge to your everyday life.

Jodi Dworkin, Extension specialist and professor in family social science

Reviewed in 2023

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