The average height for American males 20+ is 69.1 inches (175.4 cm), or 5' 9" tall. The average height of an American female 20+ is 63.5 inches (161.5 cm), or 5' 3.5" tall.
According to the CDC, the average male height around 20 years old is 69.5 in (177 cm).
For a woman raised in the United States, the average height is currently 5 feet 4 inches, or around 63.7 inches. However average heights vary, depending on where a person is born and raised. This was reported by the Centers for Disease Control and Prevention (CDC) and applies to women over the age of 20.
However, once the growth plates in the bones close, a person will generally not grow any taller. Most females reach their full adult height aged 14–16 years. Most males reach their full height by the age of 16–18 years. It is very unusual for a person to grow after the age of 18 years.
How Tall Should a 12-Year-Old Be? We can only speak to national average heights here in North America, whereby a 12-year-old girl would be between 137 cm to 162 cm tall (4-1/2 to 5-1/3 feet). A 12-year-old boy should be between 137 cm to 160 cm tall (4-1/2 to 5-1/4 feet).
The expected average height of a healthy population should be 163 cm for women and 176.5 cm for men – as defined by the WHO growth reference standards. Interestingly, the global average height is 159.5 cm for women, and 171 cm for men – it's lower than we'd expect.
Although a few people may continue growing even in their early 20s, most adults cannot increase their height after age 21 if their growth plates close. However, there are ways to maximize your height in your growing years through nutrition and exercise.
Changes in Boys
They tend to grow most quickly between ages 12 and 15. The growth spurt of boys is, on average, about 2 years later than that of girls. By age 16, most boys have stopped growing, but their muscles will continue to develop.
Increasing your height after 18 is not possible, even through nutrition and exercise, because the growth plates stop growing. The growth plates (epiphyseal plates) are present at the end of long bones.
What can I do to become taller? Taking good care of yourself — eating well, exercising regularly, and getting plenty of rest — is the best way to stay healthy and help your body reach its natural potential. There's no magic pill for increasing height. In fact, your genes are the major determinant of how tall you'll be.
According to the U.S. Food and Drug Administration, short stature means an estimated final height below 5 feet 3 inches for boys or 4 feet 11 inches for girls. The average height in the United States is 5 feet 8 inches for men and 5 feet 4 inches for women.
A major growth spurt happens at the time of puberty, usually between 8 to 13 years of age in girls and 10 to 15 years in boys. Puberty lasts about 2 to 5 years.
Some boys will reach their full adult before age 17, while others may continue growing until age 20 or 21. They'll grow around 3 inches per year during puberty, which typically occurs between ages 9 and 14 for boys.
Men are most satisfied when they are 3 inches (8cm) taller than their partners. Another study found that among men, 13.5 percent prefer to date only women shorter than them. But among women, about half (48.9 percent) preferred to date only men taller than them.
As mentioned in one of the articles one good way to see if you still have growth potential is to X-ray a wrist- the test is called a Pediatric Bone Age. It will show if your growth plates are still open. A doctor can also request lab tests- checking for hormones- such as thyroid, growth hormone and sex hormones.