Estimate your child's adult height using the Khamis-Roche method
Based on the Khamis-Roche method (1994). Originally developed using US population data. Results are estimates and actual adult height may differ. Consult a paediatrician for growth concerns.
Parents often wonder how tall their child will grow. The Khamis-Roche method, developed in 1994, is one of the most widely referenced approaches for predicting adult height from childhood measurements. Unlike simpler "double the height at age 2" rules of thumb, this method uses a regression equation that accounts for the child's current height, weight, age, sex, and both parents' heights. This calculator applies the Khamis-Roche formula to estimate your child's predicted adult height, along with a 90% confidence interval that shows the likely range. The method works for children aged 4 to 17.5 years. Predictions become more accurate as the child gets older, since less growth remains. The confidence interval narrows with age, reflecting this increased certainty. Height is influenced by both genetic and environmental factors. Genetics account for roughly 60-80% of adult height variation, which is why parental heights are a key input. Nutrition, sleep quality, general health, and hormonal factors account for the remainder. The NHS recommends monitoring children's growth using UK-WHO growth charts and consulting a paediatrician if growth patterns seem unusual.
To predict your child's adult height: 1. Select the child's sex (male or female), as growth patterns differ significantly between boys and girls. 2. Enter the child's current age in years (accepts half-year increments, e.g. 10.5). The method covers ages 4 to 17.5. 3. Enter the child's current height in centimetres. Measure without shoes, standing straight against a wall. 4. Enter the child's current weight in kilograms. 5. Enter the father's height and mother's height in centimetres. Use adult heights measured in the last few years for best accuracy. 6. The calculator instantly shows the predicted adult height, an imperial conversion, a 90% confidence interval (lower and upper bounds), and an approximate UK adult height percentile.
The Khamis-Roche method uses the following regression equation: Predicted Height = Intercept + (Height Coefficient x Child Height) + (Weight Coefficient x Child Weight) + (Mid-Parent Coefficient x Mid-Parent Height) Where Mid-Parent Height = (Father's Height + Mother's Height) / 2. The intercept and coefficients vary by the child's age and sex. The calculator uses a lookup table with values at half-year intervals from age 4 to 17.5, derived from the original 1994 study data. The 90% confidence interval is calculated as: - Lower bound = Predicted Height - (Standard Error x 1.645) - Upper bound = Predicted Height + (Standard Error x 1.645) The standard error (SE) decreases with age, reflecting greater prediction certainty for older children. At age 4, the SE is around 7.5 cm for boys and 6.5 cm for girls. By age 17, it narrows to approximately 2.8 cm for boys and 2.0 cm for girls. The UK height percentile is calculated by comparing the predicted height against adult height distributions (male mean 175.3 cm, SD 7.1 cm; female mean 161.9 cm, SD 6.3 cm).
Inputs: Child's sex: Male, Age: 10, Height: 140 cm, Weight: 35 kg, Father's height: 178 cm, Mother's height: 165 cm.
Inputs: Child's sex: Female, Age: 12, Height: 152 cm, Weight: 42 kg, Father's height: 180 cm, Mother's height: 165 cm.
Inputs: Child's sex: Male, Age: 16, Height: 175 cm, Weight: 65 kg, Father's height: 176 cm, Mother's height: 163 cm.