How accurate is the mid-parental method?

It is accurate to within ± 8 cm (about 3 in) for most children. Genetics is the dominant factor but nutrition, illness and timing of puberty can shift the final result.

What is the mid-parental formula?

Boy: ((father + mother) / 2) + 6.5 cm. Girl: ((father + mother) / 2) − 6.5 cm. The 6.5 cm reflects the average sex difference in adult height.

Why does current child height matter?

For school-age children, you can also project adult height by extrapolating their current growth percentile. Combining genetic and growth-based estimates gives a more reliable range.

Can I influence height?

Genetics accounts for about 80%. The remaining 20% is mostly nutrition (especially in the first 5 years), sleep and overall health. Beyond these, no commercially available product reliably increases final adult height.

📏 Height Predictor

Estimate a child's adult height using the mid-parental formula plus optional current-age extrapolation.

Units

Child's sex

Father's height (cm)

Mother's height (cm)

Child age (years, optional)

Child current height (optional)

⚠️ Estimate only. Final adult height varies based on nutrition, illness, timing of puberty and growth-related medical conditions. Speak to a paediatrician for individualised assessment.

About the Height Predictor

Adult height is roughly 80% genetic. The classic mid-parental method averages the parents' heights and adjusts by 6.5 cm for the child's sex.

Boy: mid-parent + 6.5 cm
Girl: mid-parent − 6.5 cm

For school-age children, the calculator also adds a simple growth-extrapolation estimate using approximate WHO/CDC ratios — useful as a sanity check on the genetic figure.

What affects accuracy

Timing of puberty (early or late onset by 1–2 yr can shift adult height by 3–5 cm)
Nutrition during the first 5 yr and during adolescence
Chronic illness or growth disorders
Step-parents or unknown biological parents — use biological parent heights for accuracy

Frequently Asked Questions

± 8 cm range — why so wide? Even with both parents' heights known, the genetic spread plus environmental factors give roughly a 16 cm prediction interval at 95% confidence.

Can a child be taller than both parents? Yes — common when one parent comes from a tall family with shorter immediate parents. Genetic recombination is unpredictable.

⚠️

Important Note: Predictions are estimates. Always consult a paediatrician for clinical growth assessment — especially if a child's growth deviates significantly from family norms.

Related Calculators

Ideal Weight Calculator — Ideal body weight using Hamwi, Devine, Robinson and Miller formulas.
BMI Calculator — Body Mass Index with WHO health context.
Body Fat Calculator — Estimate body fat % using the US Navy method and BMI-based formula.