While the exact age is hard to pinpoint, most human males finish growing physically in their early 20s. Many boys achieve complete physical maturity by the middle to late teens, while others continue to experience changes for a few more years.
Young males typically begin puberty between the ages of 9 and 16, and it can last anywhere from two to five years. The age of onset is not a reliable indicator of the duration of puberty or a person's final height, which depends on when the epiphyseal growth plates close. This usually occurs near the end of puberty. At this point, the bones stop lengthening and men reach their full height.