About this tool
The Child Height Predictor is a free, in-browser tool that estimates how tall a child is likely to be as an adult using the classic mid-parental (Tanner) method: average the parents' heights, then add 6.5 cm for a boy or subtract 6.5 cm for a girl.
Heredity is only part of the story — nutrition, health and timing of puberty all shift the outcome — so the tool also shows the commonly quoted ±8.5 cm range around the prediction, inside which most children land. Everything is computed instantly in your browser; no data is sent anywhere.
Frequently asked questions
How does the mid-parental formula work?
Predicted adult height = (mother's height + father's height) ÷ 2, plus 6.5 cm for boys or minus 6.5 cm for girls. The 6.5 cm term reflects the average adult height difference between the sexes (about 13 cm).
How accurate is the prediction?
It is a rough genetic target: roughly 95% of children end up within ±8.5 cm of it, which is the range shown. A child's own growth curve tracked by a doctor is far more informative.
Can I enter heights in feet and inches?
Switch the unit to inches and enter total inches (5 ft 10 in = 70 in). The prediction and range are shown in the same unit you chose.
Is anything stored or uploaded?
No. The calculation is a single formula that runs entirely in your browser — nothing is saved or transmitted, and the result is an educational estimate, not medical advice.