Most girls reach their final adult height between ages 14 and 16, roughly two to three years after their first period. The exact timeline depends on when puberty started, genetics, and overall health. Girls who enter puberty earlier tend to stop growing earlier, while those who develop later may continue gaining height into their late teens.
The Role of Puberty in Growth
A girl’s biggest growth spurt happens before her first period, not after. During early puberty, rising estrogen levels trigger rapid bone growth, which is why many girls shoot up several inches in a short window of time. But estrogen has a dual role: at low levels it fuels that growth spurt, and at high levels it signals the growth plates in the bones to gradually close. This is why the fastest height gain happens in the early and middle stages of puberty, then tapers off.
Once a girl starts menstruating, the growth slowdown is already underway. On average, girls grow about 3 inches (7 cm) after their first period. But that number shifts depending on timing. Data from the Fels Longitudinal Study, one of the longest-running growth studies in the U.S., shows that girls who get their first period at age 10 grow about 4 inches afterward, while those who start at 15 grow closer to 2 inches. Earlier puberty means more remaining growth; later puberty means less, because the growth plates have had more time to mature by the time menstruation begins.
When Growth Plates Close
Height growth happens at the growth plates, which are bands of cartilage near the ends of long bones. As long as these plates remain open, new bone tissue can form and lengthen the bone. Once they fuse into solid bone, no further lengthening is possible.
In girls, the earliest signs of growth plate closure at the knee appear around ages 16 to 17. Full fusion of the bones around the knee, including the lower thighbone and shinbone, typically completes between ages 20 and 22. However, the growth plates that matter most for height (in the legs and spine) largely finish their work earlier, which is why measurable height gain usually stops well before full skeletal maturity. A practical rule of thumb: once a girl has reached the final stages of puberty, her growth plates are essentially closed for height purposes.
Doctors can estimate how much growth remains by taking an X-ray of the hand or pelvis and comparing bone maturity to standardized charts. This is called a “bone age” assessment, and it’s the most reliable way to know whether a girl still has growth potential.
How Genetics Shape Final Height
Genetics account for roughly 60 to 80 percent of a person’s adult height. Pediatricians use a simple formula called mid-parental height to estimate where a girl will likely end up: take the father’s height, subtract 5 inches, add the mother’s height, and divide by 2. The result gives a rough midpoint, with most girls falling within about 2 inches above or below that number.
This formula is a starting point, not a guarantee. Nutrition, health conditions, and the timing of puberty all push the final number up or down. But if you’re wondering whether a girl will be closer to her mother’s height or her father’s, mid-parental height gives the best quick estimate.
What Can Affect Final Height
Several factors can cause a girl to end up shorter or taller than her genetic potential would predict.
- Early puberty (precocious puberty): When puberty begins before age 8, the early surge of estrogen accelerates bone maturation and closes growth plates sooner. Girls with untreated precocious puberty often end up significantly shorter than expected based on their parents’ heights. Studies show their final adult height averages about 1 standard deviation below the population mean, which translates to roughly 2 to 3 inches shorter than their genetic target.
- Chronic malnutrition or eating disorders: Conditions like anorexia nervosa cause growth to decelerate during adolescence. The hormonal disruptions that accompany severe calorie restriction, including low thyroid function, elevated stress hormones, and suppressed reproductive hormones, all interfere with normal bone growth. The one partial silver lining is that the low estrogen associated with these conditions can delay growth plate closure, leaving a window for catch-up growth if nutrition is restored before the plates fuse.
- Chronic illness: Conditions that affect nutrient absorption (like celiac disease) or hormone production (like thyroid disorders) can stunt growth if undiagnosed or untreated during the critical adolescent years.
- Nutrition and sleep: Growth hormone is released primarily during deep sleep, and adequate protein and calorie intake provides the raw materials for bone growth. Consistently poor sleep or an inadequate diet during puberty can limit height potential.
A Typical Growth Timeline
Here’s what the growth trajectory looks like for most girls. Breast development begins around ages 8 to 13, marking the start of puberty. The peak growth spurt usually happens about a year before the first period, with girls gaining 3 to 4 inches per year during this phase. The first period arrives around age 12 on average, though anywhere from 10 to 15 is normal. After that, growth slows to 1 to 2 inches per year and gradually tapers to zero.
By age 14 or 15, most girls have reached at least 95 percent of their adult height. By 16, the vast majority are done growing. A small amount of height gain (usually less than half an inch) can trickle in through the late teens for some, but it’s uncommon for a girl to grow meaningfully after 16.
If you’re tracking a girl’s growth and she’s been the same height at two consecutive annual checkups after her period has started, she has very likely reached her final height. If there’s concern about growth stopping too early or too late, a bone age X-ray can give a clear answer about whether the growth plates are still open.