Child Height Predictor

The Mid-Parent Height method is the classic target-height formula: average the two parents' heights, then add 5 inches for boys or subtract 5 inches for girls (accounting for the average height difference between adult men and women), and divide by two. Under this method, a taller Father's Height or Mother's Height always raises the predicted adult height, and the two parents contribute equally -- each inch of either parent's height moves the prediction by exactly half an inch. The Current Height Projection method works completely differently: it ignores both parents' heights entirely and instead divides the child's current height by the median percentage of adult height a child of that age and sex has reached, drawn from the CDC's own published stature-for-age percentile data (the 2000 CDC Growth Charts, National Center for Health Statistics), reflecting how much of eventual adult height a child has typically reached at a given age.

Because the two methods use disjoint inputs, changing a parent's height has no effect at all while Current Height Projection is selected, and changing the child's age or height has no effect while Mid-Parent Height is selected. Both methods report a range of plus-or-minus 8.5 cm (about 3.3 inches) around the point estimate -- the published Tanner target-height range, which spans roughly the 3rd to 97th centile of where children of those parents actually end up. Neither method accounts for nutrition, health conditions, or the wide individual variation in growth timing -- both are population-level statistical approximations, not a substitute for a pediatrician's growth-chart assessment (which can also use bone-age X-rays for a more precise estimate when medically indicated).