Mid-Parental Height Calculator

Mid-parental height is the average of the biological mother's and father's heights. It serves as the genetic 'target' height for a child. Clinical pediatricians have used this concept since the 1960s as a quick way to assess whether a child is growing in line with their genetic potential without needing an X-ray or bone-age scan.

The Tanner-Goldstein-Whitehouse formula (Arch Dis Child, 1970) calculates sex-adjusted predicted heights: For sons: predicted height = (mother's height + 5 inches + father's height) ÷ 2. For daughters: predicted height = (mother's height + father's height − 5 inches) ÷ 2. The raw mid-parental height is simply (mother + father) ÷ 2 with no sex adjustment.

The ±5 inch (≈13 cm) offset approximates the average height difference between adult men and women in the populations Tanner studied (British children, 1950s–1960s). This adjusts the shared genetic baseline to a sex-appropriate prediction. Wright & Cheetham (Arch Dis Child 1999) noted a ±4 inch offset may fit some populations better, but ±5 inches remains the dominant clinical standard worldwide.

The mid-parental height formula predicts adult height within ±3.5 inches for the majority of children. It is less precise than the Khamis-Roche method (±2.2 in for boys, ±1.7 in for girls) because it uses only parental heights — no current measurements of the child. Genetics explain approximately 60–80% of adult height variation (Silventoinen et al., 2003), with the remainder determined by nutrition, sleep, illness, and timing of puberty.

The mid-parental height method only uses parents' heights. The Khamis-Roche method (Pediatrics, 1994) also incorporates the child's current height, weight, and age, using regression coefficients derived from the Fels Longitudinal Study. This additional data captures how far along the child is in their growth trajectory, improving accuracy by roughly 1–2 inches. Use mid-parental height when your child is very young or not yet measured; use the full Height Predictor when they are age 4 or older.

Yes. The mid-parental height is routinely plotted on CDC growth charts by pediatricians to assess whether a child's growth trajectory is consistent with family genetics. A child whose measured height falls within ±2 standard deviations of their mid-parental target is considered to be growing appropriately for their genetic background, even if they are short or tall relative to the general population.

The Tanner formula was validated on Western European populations. Because average adult height and male–female height dimorphism differ across ethnic groups, there can be small systematic biases. For general planning purposes the formula remains widely applicable, but population-specific growth standards (such as those from the WHO or CDC) may be more accurate for specific groups. Consult a pediatrician for a personalized assessment.