Mid-parental height formula
The mid-parental height (MPH) formula was developed by Tanner and colleagues in the 1970s based on longitudinal growth studies and represents the single most widely used clinical tool for estimating a child's genetic height potential. For boys: MPH = (father's height + mother's height + 13 cm) / 2. For girls: MPH = (father's height + mother's height − 13 cm) / 2. The 13 cm correction accounts for the average height difference between adult males and females.
The ±8.5 cm range (representing approximately ±2 standard deviations) covers approximately 95% of children born to parents of a given height combination. This range is important context: genetic potential defines a window, not a fixed outcome. Nutrition, health status, sleep quality, and other environmental factors influence where within that window a child's final height falls. Children growing substantially outside this range should be assessed by a paediatrician.