Predict a child’s adult height from parents’ height

This calculator estimates a child's predicted adult height using the mid-parental height method, a well-known formula from pediatric growth literature. It starts by averaging both parents' heights, then adjusts for the typical height difference between adult men and women: for boys, add 13cm to the average and the result is the midpoint estimate; for girls, subtract 13cm instead. In formula form: boys = (father's height + mother's height + 13) ÷ 2, and girls = (father's height + mother's height − 13) ÷ 2.

The 13cm adjustment isn't arbitrary — it reflects the average adult height gap between men and women observed across large population studies, and it's what allows the same two parent heights to produce a sensible estimate for either a son or a daughter.

The midpoint number alone is not the whole picture, which is why this calculator also shows a typical range of plus or minus 8.5cm around it. That range represents roughly a 68% confidence interval — in other words, about two-thirds of children with those exact parent heights end up somewhere within that band as adults, while the rest fall outside it in either direction. A single midpoint number without a range overstates how precise this kind of genetic estimate actually is.

Mid-parental height is a starting point based purely on genetics, but a child's actual adult height also depends heavily on nutrition during childhood and adolescence, overall health, chronic illness, hormonal factors, and simple individual growth variation — siblings with identical parents regularly land at different points within (or outside) the predicted range.

This tool is meant for general curiosity and rough planning, not medical assessment. A pediatrician tracking a child's height and growth velocity on a proper growth chart over time — factoring in growth percentiles, bone age, and pubertal timing — gives a far more accurate and individualized prediction than any formula based on parent height alone.