Most girls stop growing in height between ages 13 and 15, while most boys reach their final height between 16 and 18. Some males continue growing into their early 20s, though this is uncommon. The exact age depends on when you enter puberty, your genetics, and your overall health during childhood.
Growth Timelines for Girls and Boys
Girls typically hit their fastest growth spurt earlier than boys, usually around age 11 or 12. After that burst, growth slows steadily and stops once puberty wraps up, generally between 13 and 15. Most girls gain very little height after their first period, which often arrives near the tail end of their peak growth phase.
Boys start their major growth spurt later, usually between 13 and 14.5 years old. During this window, it’s common to grow 3 to 4 inches per year. Growth continues after that peak but at a declining rate, and most boys reach their adult height by 16 to 18. In rare cases, males keep adding small amounts of height into their early 20s, particularly if they were late to start puberty.
What Actually Stops Your Bones From Growing
Height comes from the lengthening of your long bones, specifically the legs, spine, and arms. Near the ends of these bones, there are sections of cartilage called growth plates. Throughout childhood, these plates keep producing new cartilage, which gradually hardens into bone. This cycle of cartilage production and hardening is what makes you taller year after year.
Eventually, sex hormones (estrogen in girls, testosterone and estrogen in boys) signal these growth plates to slow down and fully harden into solid bone. Once a growth plate has completely ossified, that bone can no longer lengthen. This process usually finishes in the early twenties at the latest, leaving behind only a thin line visible on an X-ray where the growth plate used to be. It’s permanent: once your plates close, no amount of nutrition, exercise, or supplementation will add height.
Why Puberty Timing Matters So Much
Because sex hormones are what ultimately shut down growth plates, the age you start puberty has a major influence on when you stop growing. Kids who enter puberty early tend to have an earlier growth spurt but also stop growing sooner. Kids who are “late bloomers,” starting puberty a year or two behind their peers, often keep growing longer and may end up the same height or taller despite being shorter in middle school.
This is why two 14-year-olds can look dramatically different. One may have nearly finished growing while the other hasn’t hit peak growth yet. Both patterns are normal. The medical term for the late-bloomer pattern is constitutional delay of growth, and it tends to run in families. If one of your parents was a late bloomer, there’s a reasonable chance you will be too.
Genetics, Nutrition, and Other Factors
About 80 percent of your final height is determined by the DNA you inherited. Height isn’t controlled by a single gene but by a large combination of genetic variants, each contributing a small amount. This is why tall parents generally have tall children, but not always: the genetic mix can produce surprises.
The remaining 20 percent comes from environmental factors, and nutrition is the biggest one. A well-nourished, healthy, active child is likely to reach a taller adult height than a child dealing with chronic malnutrition, repeated infections, or inadequate healthcare. A mother’s nutrition during pregnancy, smoking status, and exposure to hazardous substances also play a role. In practical terms, if you grew up with adequate food and healthcare in a developed country, you’ve likely come close to your genetic height potential. Extreme dieting or serious illness during the growth years, on the other hand, can result in a shorter final height than your genes would otherwise allow.
How to Tell If You’re Still Growing
The most reliable way to know whether you have growth left is a bone age X-ray. It’s a simple X-ray of the hand and wrist that shows how mature your skeleton is compared to your actual age. A doctor can look at the growth plates in the hand bones and estimate how much growth potential remains. If the plates appear nearly closed, you’re close to your final height. If they’re still clearly open, there’s room left.
Without an X-ray, there are some practical clues. If you haven’t grown at all in the past 6 to 12 months and you’re past the typical age range for your sex, your growth plates have likely closed. For girls, being two or more years past your first period is a strong signal that growth is finished. For boys, signs like a fully deepened voice and adult facial hair patterns suggest puberty is wrapping up and height growth is nearly done.
Can You Grow After 18 or 20?
True bone growth after 18 is uncommon in females and unusual but possible in males. Some men do add a fraction of an inch between 18 and 21, particularly those who started puberty on the later side. Growth after 21 is extremely rare in healthy individuals. Any noticeable height increase after the early 20s is more likely due to improved posture, spinal decompression from stretching, or measurement variability than actual bone lengthening.
Adults can also lose height over time. Spinal discs compress gradually with age, and conditions like osteoporosis can reduce vertebral height. This process is slow and typically doesn’t become noticeable until middle age, but it’s the reason many people measure slightly shorter at 60 than they did at 25.