Adult Height Predictor

Projected adult height: mid-parental and beyond

The easiest route is the mid-parental height (Tanner formula): target = (father + mother) / 2 ± 6.5 cm, adding +6.5 cm for boys and subtracting −6.5 cm for girls (all in centimeters). Figure on a spread of about ±5 cm around that target. If you want something tighter, there are better methods. Khamis–Roche factors in current height, weight and age with no x-ray at all. Bayley–Pinneau reads bone age off a wrist x-ray against the Greulich–Pyle atlas. And following the Tanner stages I–V of puberty tells you how much growth is still on the table. Example: father 175 cm, mother 162 cm. Mid-parental for a son = (175+162)/2 + 6.5 = 175 cm (range ≈ 170–180 cm); for a daughter = (175+162)/2 − 6.5 = 162 cm (range ≈ 157–167 cm).

Applications

In pediatric endocrinology it helps work up short or tall stature and weigh therapies like recombinant growth hormone (somatropin) when there's a deficiency. Surgeons lean on it for orthopedic planning, such as an epiphysiodesis to cap final height. And in youth sports like basketball, volleyball or swimming, scouts quietly use projected adult height when sizing up talent. Keep in mind genetics pins down only about 80% of where someone ends up; nutrition, sleep, hormones and illness fill in the rest.

FAQ

How accurate is mid-parental height? About two out of three kids land within ±5 cm of the target. The misses tend to come from early or late puberty, chronic illness, or non-paternity.

Can the projection change with growth hormone or nutrition? Yes. A clinically diagnosed growth hormone deficiency, treated celiac disease, or recovery from severe malnutrition can all nudge the projection upward. A healthy child with normal hormones, though, won't gain any extra height from supplements.

When does a person reach final height? Usually around 16 in girls and 18 in boys, once the growth plates (epiphyses) close. A wrist x-ray for bone age confirms it.