A 14-year-old boy’s average height is 64.5 inches, while a 14-year-old girl’s average height is 62.5 inches. As kids grow into young adults, the difference in height gets bigger. On average, 20-year-old males are 69.7 inches tall, while 20-year-old females are only 64.2 inches tall.
This trend usually starts at age 14. At age 13, teens of both sexes are about the same height, within 0.2 inches of each other. After age 15, men are 4 to 5 inches taller on average than women.
Most people stop growing taller quickly during adolescence around age 17 or 18. This is seen as the start of adulthood in most cultures. Between the ages of 17 and 20, both men and women grow less than an inch.