When Does Puberty Start in Boys?
Published November 14, 2026 · Written from AAP, KidsHealth and other pediatric sources
Parents often ask whether their son is "on time." The honest answer is that the normal range is wide, and sources give slightly different ranges.
The typical age range
- KidsHealth tells boys that most begin puberty between 9 and 14, and tells parents that the range is 9 to 15, with the average around 10 or 11.
- Valley Children's Healthcare gives a range of 10 to 16 and says it lasts about 2 to 5 years once it begins.
- UF Health says most boys start somewhere between 9 and 16.
The differences between sources come down to the same point: the normal window is wide. That is why some seventh graders still look like young children while others look much older. Girls usually start earlier than boys, which is why many girls are taller than boys in the 7th and 8th grade.
What is the first sign?
Valley Children's says the first change in boys is enlargement of the scrotum and testes. The AAP describes a near doubling in the size of the testicles and scrotal sac as the start of puberty.
What comes next
Changes build slowly rather than all at once. UF Health says boys usually begin their growth spurt about 2 years after puberty starts. Valley Children's says boys typically have their height spurt fairly late in puberty, and that about 20 percent of adult height is gained during puberty. Voices get lower and deeper.
When to check in with the pediatrician
- Very early signs. Valley Children's defines precocious (early) puberty in boys as starting before age 9. Norton Children's advises a pediatrician visit if signs appear before the typical age range, to rule out conditions that could cause it.
- Worry about no signs. UF Health lists being worried that you are not going into puberty as a reason to talk to a doctor.
- Pain or a problem. UF Health also lists pain or a problem with the penis or testicles.
If you are unsure, a quick question to his pediatrician is always reasonable.
Good to know: This article is general education, not medical advice. If you are worried about your son's health or development, ask his pediatrician.
Sources
- Talking to Your Child About Puberty (KidsHealth, Nemours)
- Boys and Puberty (KidsHealth, Nemours)
- Physical Development in Boys: What to Expect (HealthyChildren.org, American Academy of Pediatrics)
- Puberty: Normal Growth and Development in Boys (Valley Children's Healthcare)
- Puberty in Boys (UF Health)
- When do boys start puberty? (Norton Children's)
Facts checked against these pages on November 14, 2026. See how we fact-check.