When Do Boys Stop Growing?

Several signs indicate growth has ended: height has not changed for over 12 months, shoe size has been stable for a year or more, facial hair has filled in, the voice has fully deepened, and muscle development looks adult (Tanner Stage 5). The most reliable medical method is a bone-age X-ray of the hand and wrist, which a pediatrician can use to confirm whether the growth plates are still open.

Boys' fastest growth typically happens around age 13 to 14, during the middle of puberty. At this peak, a boy can gain 3–4 inches (7–12 cm) in a single year. The total puberty growth spurt usually adds 10–12 inches (25–30 cm) to a boy's height over 2 to 5 years.

For most boys, no — by 18, the growth plates have largely closed and final adult height has been reached. However, late bloomers (boys whose puberty started after age 14) may continue growing slowly until 20 or 21. Growth beyond age 21 is extremely rare and usually indicates a medical condition that requires evaluation by a doctor.

Using CDC reference data (50th percentile), average heights are approximately:

Age 10: 4'6" (138 cm)
Age 13: 5'1" (156 cm)
Age 14: 5'4" (164 cm)
Age 16: 5'8" (174 cm)
Age 18+: 5'9" to 5'10" (175–177 cm)

These are averages — individual boys can fall above or below and still be healthy.