The age when your son stops growing has a lot to do with when he starts puberty and whether or not he's a late bloomer. Experts explain what to expect, plus a few common height prediction methods doctors use.

By Maria Carter
December 23, 2019
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It's common knowledge that boys don't mature at the same pace as girls, but that growing gap isn't as wide before age 10.

"Growth spurts aren't common in the 3-10 age range," explains Zoltan Antal, M.D., chief of pediatric endocrinology at New York-Presbyterian Komansky Children's Hospital and Weil Cornell Medicine. "Most prepubescent children grow 2 inches or 5 centimeters a year on average."

Girls do most of their growing at the start of puberty, which can be as early as age 8 for them, and reach their final adult height around two years after their first period. Boys experience peak acceleration of growth much later, usually between ages 13 to 15, since they typically enter pubertal development around age 12 (though some "early bloomers" may start puberty at 9 or 10, says Dr. Antal).

At what age do you stop growing in height? The answer depends on your sex. Although boys get a late start compared to their female peers, they eventually catch up, and then some. Most girls stop growing taller by age 14 or 15, but, after their early teenage growth spurt, boys continue gaining height at a gradual pace until around 18.

Height Prediction for Boys

While there's no 100 percent accurate way to determine how tall children will be, there are two methods pediatricians commonly employ to predict adult height for boys.

Most doctors use what's known as a "mid-parental height calculator" to determine a range of how tall boys will grow to be, says Danton Kono, M.D., pediatrician with Dignity Health Mercy Medical Group in California, though he's quick to add that the method is "still very inaccurate."

To get the estimated range, you take the boy's mother's height and add 5 inches, then average that number with the boy's father's height. The resulting height, plus or minus 3.35 inches, is how tall you can expect the boy to become. For instance, if Dad is 5'10" and Mom is 5'2", you would add 5'10" to 5'7" and divide that sum by two to get 5'8½"—their son should grow to be 5'8½", give or take a few inches.

Dr. Antal prefers another method. "For a child who's going through puberty, you find their height percentile on a growth chart, and follow the corresponding curve out," he explains. For example, if you look at the Centers for Disease Control and Prevention (CDC) growth chart for boys 2 to 20 years, a 13-year-old boy who is 5'1" (61 inches tall) is in the 50th percentile. Based on that curve, he should reach an adult height between 5'9" or 5'10" (69-70 inches).

The CDC growth chart also shows weight-for-age percentiles that allow parents to estimate what their son might weigh in the future. Using the same example of the 50th percentile, a 13-year-old boy who weighs just over 100 lbs can expect to weigh roughly 155 by the time he's an adult, if he continues developing at an average pace.

When to See a Doctor

If it seems like every other kid is growing but not your own, don't worry just yet. "Children with delayed growth, what's known as constitutional growth delay, experience slow and steady growth," says Dr. Kono. "In this scenario, even though a boy may not be maturing very fast, he's still going to be a normal adult height."

Pediatricians can do a bone age X-ray in office to determine if your son's growth is on track. "If I get an X-ray of a 14-year-old boy and his bones look like those of a 12 year old, that tells me he's still got five or six years of growth left and he won't achieve his final adult height until maybe even college age," says Dr. Kono.

However, if your son is falling off of the growth curve and not catching up with his peers, there could be something medically wrong, like a growth hormone deficiency, he adds.

"It's important to ask your pediatrician about where the child is in puberty and whether they are growing appropriately for their stage of puberty," says Dr. Antal. If you wait until your son is almost finished with puberty, there's not much an endocrinologist, a physician who specializes in conditions relating to hormones, can do to help.

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