When do boys stop growing?

April 19, 2019
When do boys stop growing?

One day you’re holding your baby boy in your arms, and the next, you’re staring up at him in amazement. How did this happen? Where did the time go?! And, perhaps most pressing (to your wallet and your fridge), at what age do boys stop growing?

If you feel like your once onesie-sized son is growing at the speed of light, you’re not totally wrong. In a matter of a few years, boys can shoot up almost a foot in height, leaving you looking up at him.

From the time frame of puberty to the role genetics play in height, experts weigh in on what to expect from your growing boy. And to think he once fit in the crook of your arm!

At what age do boys stop growing?

Just as your son took his first steps at a different age than your friend’s baby, the range for boys to stop growing varies. Typically, though, it occurs between 16 and 18 years old.

“Boys will stop growing when their growth plates have fused,” says Dr. Jason Klein, a pediatric endocrinologist at Hassenfeld Children’s Hospital at NYU Langone. “On average, this occurs around age 16, but boys who have early pubertal development might reach this point sooner, and boys with delayed puberty might grow for longer. Most boys will reach their full maturity, which includes growth and body changes, by age 18 years.”

Dr. Arik Marcell, associate professor of Pediatrics at Johns Hopkins Children’s Center, explains that the stages of pubertal development (and, consequently, growth) can be broken down using the Sexual Maturity Rating scale, which puts pre-pubertal boys at a rating of 1 and fully-grown men at 5.

“Each stage lasts about 1 to 1.5 years,” Marcell says. “Prior to a boy’s peak height velocity, they typically gain about 2 inches per year. Peak height for boys is usually achieved during Sexual Maturity Rating 4, where they’re growing about 3.5 to 4 inches per year, to achieve an average total height increase of 11 inches.”

What role do genetics play in height?

If dad’s tall, will your son be towering over everyone in a matter of time? Possibly, but that’s only one piece of the puzzle.

“Growth is determined by many factors, one of which is the genetic makeup of the family,” says Klein. “Sometimes doctors calculate the ‘mid-parental height,’ which is a way of figuring out where, based on the heights of the parents, we would expect a child to be growing toward. This is only one factor, though. The onset and timing of puberty plays a role in the final height of a child, as well as other medical conditions or genetic disorders.”

On the other hand, though, the timing of puberty can often be accredited to genetics.

“It is common for children of parents with later puberty to have late onset of puberty themselves, and the same is true for parents with early puberty to have kids with early development,” says Klein.

When does puberty start for boys?

If there are girls towering over your 10-year-old son, don’t worry. Girls typically start puberty first, and can have their first adolescent growth spurt two years before boys. On average, puberty begins at about 10 years old for boys, but depending on your race, could be earlier.

“Puberty for boys starts around 10, but there are differences in racial background,” Klein says. “For example, the average age of the start of puberty in African American boys might be closer to 9 years. There is a wide range of normal for boys to start puberty — anywhere between 9 to 14 years. On average, boys will be in puberty for around five years.”

Physical changes during puberty

In addition to watching your son surpass you in height, you can expect to see a number of other physical changes in him during puberty.

“The notion of boys being all hands and feet during adolescence, particularly in the early parts of puberty, is somewhat true, because the limbs grow before the trunk,” says Klein, adding that, as puberty progresses, your son’s height will increase and catch up with his long arms and lanky legs.

Additional physical signs of puberty are an increase in body hair (particularly under the arms and in the pubic region), testicular and penile enlargement, as well as the oft-dreaded problematic skin.

“Rising testosterone levels may result in acne, as well as the development of adult odors,” says Klein. “Sperm in the urine and nocturnal emissions — aka ‘wet dreams’ — tend to happen toward the end of puberty, usually around or following the peak growth spurt.”

Klein also notes that many boys (upward of 50%) may even develop a small amount of breast tissue called gynecomastia at around 13 years old.

“This is common and typically normal,” he says.

Some kids may experience growing pains during puberty — particularly if they play sports that involve running, jumping or climbing. These “pains” typically come and go and feel more like a throbbing sensation in the front of the thighs, behind the knees or in the calves.

How to support your son during puberty

If there are two things your son will need during adolescence, it’s sleep and healthy food.

“During puberty, children’s bodies are growing and changing very rapidly, so they’ll need additional energy in the form of nutrition,” says Marcell. “Also, in early puberty, there’s an increase in the nighttime release of reproductive endocrine hormones, which reinforces the importance that all children and adolescents get the appropriate level of sleep that they need, which is upwards of 8.5 to 9.5 hours per night.”

Another thing your child will need during puberty? Compassion and understanding.

“Mood changes are common during puberty, and many boys will have unexpected mood swings, self-esteem issues, aggression or even depression,” says Klein.

It may not always be easy, but try to remember: As hard as your child’s teenage years can be for you, they can be even more difficult for your (really tall) son.

Tips and stories from parents and caregivers who’ve been there.

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