Child Height Predictor – How Tall Will My Child Be?

A child height predictor based on both parents

This child height predictor estimates how tall your son or daughter is likely to be as an adult. The main estimate is the mid-parental or “target” height — the formula paediatricians use, published by Tanner and colleagues in 1970 — shown as a range rather than a single number, because two children of the same parents can easily differ by 10 cm or more.

If you add your child’s age and current height, the tool also places them on the CDC stature-for-age growth chart and projects that same centile forward to age 20. When both methods agree you can be a little more confident; when they disagree, the range is the honest answer.

Heights can be entered in centimetres or in feet and inches, and the result is shown in both.

How to use the Child Height Predictor

1. Choose Boy or Girl and the unit, cm or ft + in.
2. Enter the mother’s and father’s heights (measured, not guessed, if you can).
3. Optionally enter your child’s age (2–17 years) and height now.
4. Read the target height, the likely range and, if given, the growth-curve projection and current centile.

Child Height Predictor features

The child height predictor formula

Boys: (father’s height + mother’s height + 13 cm) ÷ 2. Girls: (father’s height + mother’s height − 13 cm) ÷ 2. In inches, use 5 instead of 13. The 13 cm is the average difference between adult men and women.

Worked example: a mother of 160 cm and a father of 175 cm. For a son: (175 + 160 + 13) ÷ 2 = 174 cm, with a likely range of 165.5–182.5 cm. For a daughter: (175 + 160 − 13) ÷ 2 = 161 cm, likely 152.5–169.5 cm.

The growth-curve projection converts your child’s height into a z-score with the CDC LMS method, z = ((height ÷ M)^L − 1) ÷ (L × S), then finds the height with the same z-score at 20 years.

How accurate is it — and what is left out

• The ± 8.5 cm range covers about 95% of children; roughly 1 in 20 ends up outside it.
• Children often cross centiles in the first two years and again in puberty, so the growth-curve projection is least reliable under 3 and between about 10 and 15, especially for early or late developers.
• The CDC charts describe US children. Indian children are often on lower CDC centiles while growing normally — the IAP publishes Indian charts. The mid-parental method is family-based and travels better.
• The Khamis–Roche method (current height, weight and parents’ heights) is not included because its coefficient table could not be verified against the original paper. Bone-age methods need an X-ray and a specialist.
• Nutrition, sleep and health matter: chronic illness, coeliac disease or hormone problems can slow growth.

When to talk to a doctor

Ask your paediatrician if your child is falling across centile lines, is far shorter or taller than the family pattern, or shows signs of puberty before 8 (girls) or 9 (boys), or none by 13 or 14. Plot measurements over time with the child growth percentile calculator, and convert units with the height converter.