Child Height Predictor
Estimate your child's likely adult height from both parents' heights, and optionally see their current growth percentile.
Source: WHO Child Growth Standards (2006) and WHO Reference 2007 · 2006 (ages 2–5), 2007 (ages 5–19) · last verified 2026-09-12
How this estimate is derived
- Model:
- Height-for-age z-score and percentile against the WHO growth reference
- Data:
- WHO Child Growth Standards (2006) and WHO Reference 2007 · 2006 (ages 2–5), 2007 (ages 5–19)
- Implementation last reviewed:
- 2026-08-29
- Purpose:
- Educational comparison against population reference data; not a clinical growth assessment.
How this is calculated
Predicted adult height uses the mid-parental height method: average both parents' heights, then add 6.5cm for a boy or subtract 6.5cm for a girl (equivalent to a ±13cm adjustment before averaging) to account for the typical adult height gap between sexes. A 95% range of ±10cm is shown around that prediction. If you provide your child's current age and height, their growth percentile is calculated against WHO height-for-age reference data for the same age and sex, using linear interpolation between the nearest whole-year reference points.
With this calculator's default inputs — a 180cm father and 165cm mother, predicting for a boy — the mid-parental average is (180 + 165) / 2 = 172.5cm, plus 6.5cm for a boy gives a predicted adult height of 179cm, with a 95% range of roughly 169cm to 189cm. The method is a genetic starting point rather than a fixed outcome: it explains a large share of the variation in adult height across a population, but individual results still depend on the nutrition, health, and growth environment a child actually experiences.
Frequently asked questions
- How accurate is the mid-parental height method?
- It's a widely used estimate, not a guarantee — about two-thirds of children end up within about 8-10cm of the prediction, which is why this tool shows a 95% range (±10cm) rather than a single number. Genetics from both parents matter, but nutrition, health and other factors also influence final adult height.
- What does the growth percentile mean?
- It compares your child's current height to WHO reference data for children of the same age and sex. A 60th percentile means your child is taller than about 60% of children that age and sex. It's a snapshot, not a prediction — percentiles can shift as children grow, especially around puberty.
- Why does the formula add or subtract 13cm?
- It corrects for the average height difference between adult men and women (about 13cm) so the mid-parental average lands on a sensible target for the child's own sex.
- What reference data is the growth percentile based on?
- WHO Child Growth Standards (ages 2-5) and the WHO Reference 2007 (ages 5-19), height-for-age, by sex — the same reference data used in pediatric growth charts worldwide.
- Can I use this in my own app?
- Yes — every calculator on Stupidly Clever has a matching REST API and MCP tool that runs the same underlying logic.
- At what age is a child's adult height predictable?
- Accuracy improves significantly after puberty — the mid-parental method is most reliable from about age 8+ for girls and 10+ for boys, once growth patterns are established. For younger children, treat the estimate as indicative rather than definitive.
- What factors other than parental height affect a child's adult height?
- Nutrition, sleep, chronic illness, and hormonal health all influence growth. The mid-parental target assumes good health and adequate nutrition throughout childhood; children who experience significant illness or malnutrition may not reach their genetic potential.