The average height for a 13-year-old boy in the USA is 61.5 inches, while the average height for a 13-year-old girl in the USA is 62 inches. Average heights vary between 13-year-old girls and boys partially because of the onset of puberty, which tends to begin earlier in females than in males.
Although the measurements above are considered average, a wide height range is considered normal for both boys and girls. Both genders are put on a sliding percentile scale, in which the 50th percentile corresponds to an average height. Boys and girls are regularly placed at the more extreme ends of the scale and are still considered perfectly healthy. Because all teens are unique, it is best to contact the child's primary care physician with any concerns.