Child Height Predictor

Genetics carries a large share of the responsibility for how tall a child eventually becomes, and the mid-parental method is the long-standing way of turning that inheritance into an estimate of adult height. This tool applies that method to project where your child's growth may be heading, which can be useful for setting expectations and following their development. It is not a fixed forecast, only a starting estimate.

At its core the method averages the biological mother's and father's heights, then adjusts that midpoint for the child's sex. For a boy, 2.5 inches (6.35 cm) is added to the parental average; for a girl, 2.5 inches (6.35 cm) is subtracted. That shift reflects the typical height gap between adult men and women and grounds the estimate in growth patterns seen across populations worldwide.

Several influences beyond genes shape final height, including nutrition, general health, and the conditions a child grows up in, so the output stays an estimate rather than a promise. Accuracy depends on entering the biological parents' heights and on accounting for any significant medical condition that can stunt growth; leaving those out is where projections tend to go wrong. The calculator shows a likely range of 3.4 inches (8.6 cm) either side of the prediction. In a study of 419 children aged 8-9, 90% were within about two centile spaces of their mid-parental height, but children of unusually tall or short parents ended up closer to average than the formula predicts (Wright and Cheetham, 1999).