The average height of a teenage boy depends heavily on his age, since boys grow dramatically between 12 and 18. A 13-year-old boy in the US averages about 5 feet 1 inch, while an 18-year-old averages about 5 feet 9 inches. That eight-inch difference reflects one of the most rapid growth periods in a male’s entire life.
Average Height by Age
Based on CDC growth chart data for US males, here are the approximate average (50th percentile) heights at each age:
- 12 years: 4 feet 11 inches (149 cm)
- 13 years: 5 feet 1 inch (156 cm)
- 14 years: 5 feet 4 inches (164 cm)
- 15 years: 5 feet 7 inches (170 cm)
- 16 years: 5 feet 8 inches (173 cm)
- 17 years: 5 feet 9 inches (175 cm)
- 18 years: 5 feet 9 inches (176 cm)
These are averages, meaning half of boys at each age will be shorter and half will be taller. A “normal” range is quite wide. At age 14, for example, a boy anywhere from about 5 feet to 5 feet 8 inches falls between the 10th and 90th percentiles, both perfectly healthy.
When the Growth Spurt Happens
Boys hit their peak growth speed at an average age of 13.7 years, though the timing varies by about a year and a half in either direction. During this peak, the average boy grows roughly 4.4 inches (11.3 cm) in a single year. That’s noticeably faster than the 2 to 2.5 inches per year boys typically gain during childhood.
The growth spurt doesn’t arrive all at once. Boys usually start accelerating around age 11 or 12, reach peak speed around 13 to 14, and then gradually slow down over the next few years. This is why the biggest jump in the height chart above happens between ages 13 and 15, while gains after 16 are much smaller.
If your son or a boy you know seems shorter than his peers at 13 or 14, it often comes down to timing. A boy who enters puberty later will hit his growth spurt later, sometimes catching up entirely by 16 or 17. Pediatricians track this using growth charts over time rather than relying on a single measurement.
What Determines a Boy’s Final Height
Genetics account for roughly 80 percent of a person’s adult height. The remaining 20 percent comes from environmental factors, with nutrition being the most significant. This means a boy with two tall parents will very likely be tall himself, but poor nutrition during childhood and adolescence can prevent him from reaching his genetic potential.
Adequate protein, calcium, vitamin D, and overall calorie intake all support healthy bone growth. Chronic illness, severe stress, and sleep deprivation can also suppress growth, since growth hormone is released primarily during deep sleep. None of these factors will make a boy grow beyond what his genetics allow, but they can hold him back if they’re lacking.
When Boys Stop Growing
Growth stops when the growth plates at the ends of long bones fully close. In boys, this process begins as early as age 14 and finishes by age 19 in essentially all males. The timeline varies by ethnicity and individual: research on bone fusion shows that African-American and Mexican-American males can reach complete fusion as early as 14, while European-American males typically don’t show complete fusion until at least 16.
Most boys gain very little height after 16 or 17. The common belief that men keep growing into their mid-20s is a myth. While some boys who enter puberty late may still add a small amount of height at 18 or 19, the vast majority of growth is finished by the end of high school. Any height change after the growth plates close is not true bone growth.
How to Track Growth at Home
If you’re wondering whether a teenage boy is growing normally, the most useful approach is tracking height over time rather than comparing to a single average. Measure height at the same time of day (morning is most accurate, since spinal compression throughout the day can subtract nearly half an inch by evening) and plot it every few months.
A consistent position on the growth chart matters more than the exact percentile. A boy who has always been at the 25th percentile and stays there is growing normally. A boy who drops from the 50th to the 15th percentile over a year or two may warrant a closer look, even if his actual height still falls within the normal range. Similarly, a boy who shows no measurable growth over a full year during ages 12 to 15, when he should be in or near his growth spurt, is worth discussing with a doctor.