Height Calculator
Predict adult child height using Mid-Parental Target Height clinical genetic equations.
Height Prediction
Predicting adult height, and what it cannot do
The most common estimate is the mid-parental method: average the parents' heights, then add 6.5 cm for a boy or subtract 6.5 cm for a girl. It is simple and reflects the fact that height is strongly heritable — genetics accounts for the large majority of the variation between people in well-nourished populations.
Its accuracy is limited in a specific way. The prediction carries a range of roughly ±8-10 cm, which is wide enough that it should be read as a band rather than a figure. Children regularly finish outside their mid-parental estimate, and a child considerably taller or shorter than both parents is unremarkable. Clinicians rely on growth-chart percentiles tracked over time, which detect a change in trajectory far more usefully than any single prediction.
Environment matters where it is limiting. Nutrition, sleep, chronic illness and endocrine conditions all affect final height, which is why average heights in many countries rose substantially across the twentieth century without any genetic change. Growth plates typically close around 14-16 in girls and 16-18 in boys, after which height is fixed — and a growth pattern that concerns you is a question for a paediatrician rather than a calculator.
Frequently asked questions
What is the mid-parental height formula?
For boys: (Father's height + Mother's height + 13 cm) / 2. For girls: (Father's height + Mother's height - 13 cm) / 2.
How accurate is adult height prediction?
The mid-parental method predicts adult height within about 8-10 cm either side for most children, which is a wide band. Bone-age radiography combined with the Bayley-Pinneau method is more precise. Genetics accounts for roughly 80% of height variation, with nutrition and health explaining most of the rest.
What is the mid-parental height formula?
For boys, add the parents' heights in centimetres, add 13, and divide by two. For girls, subtract 13 instead of adding. The 13 cm reflects the average adult height difference between the sexes. The result is a midpoint estimate, not a ceiling or a floor.
When do children stop growing?
Growth plates typically close around 14-16 in girls and 16-18 in boys, though late developers can continue into their early twenties. Peak growth velocity occurs during puberty, and most of the final height is reached within two years of that peak. Persistent concerns about growth rate are worth raising with a paediatrician.