A closer look at the family target height clinicians use as one part of a growth assessment.
Uses parents’ heights only. It does not estimate how much growth remains.
Enter both parents’ heights to see an adult height estimate and a family target range.
Method: mid-parental heightWhat height might be expected from the family’s adult heights?
How can a child’s current measurements inform an adult-height estimate?
How is a child’s measured growth changing over time?
Choose the model based on the measurements you have. The family target range belongs only to the parents-only method; it is not a Khamis–Roche error range.
Khamis–Roche combines a child’s current height and weight with the unadjusted mean of both biological parents’ heights. Separate coefficients for age and sex give each input a different weight. Adding measurements changes the model; it does not guarantee greater accuracy for every child.
Khamis–Roche: adult height = intercept + stature coefficient × H + weight coefficient × W + parent coefficient × M. H is current height in inches; W is weight in pounds; M is the unadjusted mean parent height in inches. The equation returns inches, then converts to centimeters.
This calculator accepts 4 years 0 months through 17 years 6 months. For younger children, the parents-only method can provide family-height context. Outside the supported ages, we show an error rather than extrapolating or switching formulas automatically.
The original model was developed using 223 white American boys and 210 white American girls in the Fels Longitudinal Study. It does not measure bone age or the timing of puberty. Results may differ for children with other backgrounds or conditions affecting growth. We show a point estimate without a personal prediction interval.
For a 12-year-old boy who is 150 cm tall and weighs 40 kg, with a mother of 160 cm and a father of 180 cm, the adult-height estimate is 177.8 cm. The parents-only method gives 176.5 cm for the same family. These are separate model outputs, not endpoints of a range.
UW MSK Radiology — Adult Stature Predictor · Khamis & Roche (1994), Pediatrics 94:504–507
With parents’ heights in centimeters, add 13 cm for the male formula or subtract 13 cm for the female formula, then divide the total by two. Convert imperial measurements to centimeters first so the same formula is used in either unit system.
Male: (mother + father + 13 cm) ÷ 2
Female: (mother + father − 13 cm) ÷ 2
With a mother of 165 cm and a father of 180 cm, the male formula gives 179 cm, with a reference range of 170.5–187.5 cm. The female formula gives 166 cm, with a reference range of 157.5–174.5 cm.
The Royal Children’s Hospital Melbourne describes a normal final-height range of 8.5 cm on either side of mid-parental height. We label this a family target range. It is not a calculated confidence interval for your child, and the calculator does not assign a probability to the result.
It offers context about inherited height. It does not require a child’s age, weight or current height. It does not estimate the amount of growth remaining, predict puberty timing or change an adult’s measured height.
Changes in growth rate, health conditions, nutrition and treatment can affect eventual height. This formula cannot account for those factors. It also requires both biological parents’ measured adult heights. The two traditional sex adjustments do not model individual hormonal or treatment history.
Inputs of 100–250 cm are a practical data-entry guardrail, not a clinical validation range. If your family’s measurements fall outside it, seek an individual assessment rather than substituting different values.
Royal Children’s Hospital Melbourne: Short stature referral guidance (reviewed July 2025; checked October 29, 2026). The guidance provides the 13 cm formula and ±8.5 cm range.