A worked example
A father at 178 cm and mother at 165 cm predicts a son's adult height of about 178 cm, or a daughter's at about 165 cm.
Frequently asked questions
Why does the formula add or subtract 13 cm?
It accounts for the average height difference between adult men and women — adding roughly half that gap for a son, and subtracting it for a daughter, centers the prediction around the typical sex-based difference.
How accurate is this prediction really?
It's a rough genetic estimate, not a guarantee — actual adult height is also shaped by nutrition, health, and individual growth variation. The true result falls within about ±8.5cm of the prediction roughly two-thirds of the time.
This is a general estimate for informational purposes only, not a medical prediction — consult a pediatrician for any specific growth concerns.