How TallSoon estimates adult height

Khamis–Roche

For ages 4 through 17½, this method combines current height, weight, sex, age, and both parents’ heights. The published study reports average 90% error bounds of about ±5.3 cm for boys and ±4.3 cm for girls in its study population. Those are not guarantees for an individual child.

The engine selects the nearest half-year coefficient row for sex and age. It uses a row only when at least two independent sources verify it. Height and mid-parent are converted to inches, and weight to pounds, for the published equation.

MP (in) = (mother (in) + father (in)) / 2
PAS (in) = intercept + stature coefficient × height (in) + weight coefficient × weight (lb) + mid-parent coefficient × MP (in)
Adult estimate (cm) = max(current height (cm), PAS (in) × 2.54)

Mid-parental height

This family-height target uses the average heights of both parents and an adjustment by sex. The displayed target range is approximately ±8.5 cm, based on the cited paper. It is a broad family estimate, not a forecast of an individual outcome.

Boys: (mother height (cm) + father height (cm) + 13 cm) / 2
Girls: (mother height (cm) + father height (cm) − 13 cm) / 2

Percentile projection

This illustrative method reads today’s height-for-age position on the selected CDC or WHO reference and projects that position to the adult end of the reference. Growth patterns can change, so this is not a confidence interval or a guarantee.

The engine selects or interpolates the LMS row for sex and age in months. It converts today’s height X to a z-score, then reads that z-score on the reference’s adult LMS row. The displayed band uses z ± 0.5 and is illustrative.

z = ((X / M)^L − 1) / (L × S)
When L = 0: z = ln(X / M) / S
Adult estimate = Mₐ × (1 + Lₐ × Sₐ × z)^(1 / Lₐ)
When Lₐ = 0: adult estimate = Mₐ × exp(Sₐ × z)

Growth references and limits

CDC and WHO growth references describe populations. They are not endorsements of TallSoon and may not fit every child or population. The bundled source tables and coefficient provenance are documented in the project source.

Published sources

• Khamis HJ, Roche AF. Predicting adult stature without using skeletal age: the Khamis–Roche method. Pediatrics. 1994;94(4 Pt 1):504–507. Pediatrics article
• Tanner JM, Goldstein H, Whitehouse RH. Standards for children’s height at ages 2–9 years allowing for height of parents. Archives of Disease in Childhood. 1970;45:755–762. PubMed record
• Kuczmarski RJ et al. 2000 CDC Growth Charts for the United States: methods and development. Vital and Health Statistics. 2002;(246). CDC report
• de Onis M et al. Development of a WHO growth reference for school-aged children and adolescents. Bulletin of the World Health Organization. 2007;85:660–667. WHO reference