The standard height for boys is an average of 50.4 cm at birth, 68.4 cm at about six months, 76.5 cm at one week of age, and 88.5 cm at two weeks of age, with an average height increase of about 7-8 cm per year from two weeks of age until puberty. If a child grows less than 5 cm during this period, he or she may be at the level of short stature. After puberty, height growth averages 10-12 cm per year, or possibly more depending on genetic factors. Boys are usually at 159.5cm in height by the age of 13 is the average, 165.9cm by the age of 14, 169.8cm by the age of 15, and 172.7cm by the age of 18, which is the average lifetime height of our boys.