How tall will you be?

The Khamis-Roche method (Khamis & Roche, Pediatrics 1994) predicts adult height using current age, height, weight, sex, and parents' heights — without requiring bone-age X-rays. It was validated against the Fels Longitudinal Study (over 900 participants tracked from childhood to adulthood). It remains the most accurate non-invasive height prediction method available, with a typical error of ±2.2 inches for boys and ±1.7 inches for girls.

The published Khamis-Roche method is accurate to within ±2.2 inches for approximately 80% of boys and ±1.7 inches for approximately 80% of girls. Our implementation uses verified coefficients from the published paper as anchors, with interpolated values for other ages — making this a close approximation of the full Khamis-Roche method. Individual results vary based on nutrition, sleep, puberty timing, illness history, and other factors.

Genetics account for approximately 60–80% of adult height variation. The Khamis-Roche formula uses midparental height (average of mother's and father's heights) as a proxy for genetic height potential. This single input dramatically improves prediction accuracy compared to methods that use only the child's current measurements. Unlike the Tanner mid-parental method, Khamis-Roche doesn't add or subtract a fixed sex offset — the sex difference is captured in the age- and sex-specific regression coefficients.

The Khamis-Roche method works for ages 4–17.5 (boys) and 4–16.5 (girls). Accuracy tends to be highest in the 8–14 age range, before peak puberty uncertainty. Very young children (4–6) still have many years of growth ahead, and very late-puberty teenagers (16–17 boys) have much less growth remaining, both of which increase the difficulty of prediction. The ±2 inch confidence range reflects this inherent uncertainty.

Growth plates (epiphyseal plates) in the long bones close as puberty ends. For most females, the height-relevant growth plates fuse between ages 13–17. For most males, fusion occurs between ages 15–19. Once growth plates are fully closed, no further height increase is possible. Our Growth Plate Status quiz can help estimate where you are in this process based on your age, puberty stage, and growth velocity.

The underlying method (Khamis-Roche) is the same one pediatricians and pediatric endocrinologists use for non-invasive height prediction. However, clinical assessments may also include bone-age X-rays (Greulich-Pyle method), which provides additional accuracy. This calculator is for educational estimation only and is not a substitute for professional medical evaluation.

The simpler mid-parental height formula (Tanner method) just adds or subtracts a fixed offset from the average of the parents' heights: boys = (father + mother + 5") / 2, girls = (father + mother - 5") / 2. The Khamis-Roche method is significantly more accurate because it also factors in the child's current height, weight, and age — capturing how far along they are in their growth trajectory, not just their genetic potential.