For most girls, puberty finishes between ages 14 and 16. For most boys, it wraps up between 16 and 17. That said, some physical changes (especially height) can continue into the early 20s for boys, and the full biological picture of adolescent development extends well beyond when the visible changes stop.
When Girls Finish Puberty
Girls typically begin puberty between ages 8 and 13, and the entire process takes roughly two to four years. Physical changes like breast development, body hair growth, and widening of the hips progress through predictable stages. Menstruation usually begins about two to three years after breasts start developing, and most girls reach their adult height within one to two years after their first period.
Growth plates, the soft areas of cartilage near the ends of bones that allow them to lengthen, usually close between ages 13 and 15 in girls. Once those plates harden into solid bone, height growth is done. By 15 or 16, the vast majority of girls have completed the physical changes of puberty and reached their final adult body composition.
When Boys Finish Puberty
Boys generally start puberty later, between ages 9 and 14, and tend to finish around 16 to 17. The sequence includes growth of the testicles, deepening of the voice, facial hair, and a significant growth spurt that typically peaks around 13 to 15. Growth plates in boys close later than in girls, usually between ages 15 and 17.
Most boys reach their adult height by 17, but some continue growing through their early 20s. This lingering growth is uncommon and usually adds only a small amount of height. By 18, hormone levels in boys have typically stabilized at adult ranges, marking the biological end point of puberty even if a bit of growth remains.
What Counts as “Finished”
Clinicians track puberty using a five-stage system that describes the progression of sexual characteristics. The final stage represents full adult development: mature body hair patterns, fully developed breasts or genitalia, and stable adult hormone levels. This final stage should be reached by age 18 for both sexes. If it hasn’t, a doctor may evaluate for underlying causes.
On the other end of the spectrum, if puberty hasn’t started at all by age 15, that’s considered delayed. Delayed puberty is usually just a matter of timing, especially in boys with a family history of late bloomers, but it can occasionally signal a hormonal or nutritional issue worth checking out.
What Affects How Long Puberty Lasts
Genetics play the biggest role in when puberty starts and how long it takes. Studies of identical twins show that the timing is highly inheritable, and large genetic studies have identified over 100 regions of the genome linked to the age of first menstruation in girls. Still, those genetic signals explain only a small fraction of the variation, which means environment matters too.
Body fat is one of the strongest non-genetic factors, particularly for girls. Higher body fat sends metabolic signals that can trigger puberty earlier. Girls who enter puberty early tend to spend more time in the process overall and face a higher risk of obesity later in life. Nutrition, general health, and chronic stress also influence the timeline, though their effects are harder to quantify on an individual level.
Physical Puberty Ends Before the Brain Matures
One important distinction: physical puberty and brain development finish on very different schedules. The visible, hormonal changes of puberty are largely complete by the late teens. But the brain keeps maturing until the mid-to-late 20s. The area behind the forehead, responsible for planning, impulse control, and weighing consequences, is one of the last parts to fully develop.
This gap explains a lot about the late teen and early adult years. You may look physically grown, but the neural wiring for complex decision-making is still being refined. It’s why the American Academy of Pediatrics extends its adolescent health recommendations through age 21, even though the physical markers of puberty are long finished by then.
The Short Answer by Age
- Girls: Most physical changes complete between 14 and 16. Growth plates close around 13 to 15. Adult hormone levels stabilize by 18.
- Boys: Most physical changes complete between 16 and 17. Growth plates close around 15 to 17. Some height growth can continue into the early 20s.
- Brain development: Continues until the mid-to-late 20s, well after the body finishes puberty.
So if you’re 16 or 17 and wondering whether you’re done changing, the answer depends on your sex and your individual timeline. Most of the major physical shifts are behind you by the late teens, but subtle changes in body composition, bone density, and brain function continue for years afterward.