Height Predictor

Estimate a child's adult height with the classic mid-parental method from both parents' heights — with an honest range around it.

All calculations happen entirely in your browser. Your family heights never leave your device.

Child's sex
Child's current age & height (optional)

For context only — these values are not used in the prediction formula.

Predicted adult height
—
—
Likely range (±8.5 cm)
—
—

General information only — not medical advice; consult a professional.

How It Works

This tool uses the mid-parental method — the classic child-from-parents height estimate used in growth clinics — and it is honest about being a family average with a wide band around it.

The Mid-Parental Formula
Boys: predicted adult height = (mother + father) ÷ 2 + 6.5 cm. Girls: (mother + father) ÷ 2 − 6.5 cm. The ±6.5 cm shift simply reflects the average height difference between men and women — you are taking the parents' midpoint and moving it toward the child's sex. The displayed range adds ±8.5 cm on top: a generous band, chosen because this method is a family average, and most children do land within a few inches of it.
What It Is Not
It is not Khamis-Roche (a more refined method that needs the child's own height and weight at age 5+ and validated percentile tables) and not a bone-age assessment (an X-ray that estimates remaining growth). It only works the other direction — parents' heights in, child's future out — so it cannot "predict" height for an adult who is already done growing, and the optional child age/height fields above are deliberately decorative context, never part of the math.
Beyond Genes
Twin and family studies put height's heritability around 80% in well-nourished populations — the remaining variation comes from childhood nutrition, sleep, chronic illness and the timing of puberty, none of which a formula can see. This is also why a real child is tracked by growth-chart percentiles with a doctor: what matters clinically is staying near their own curve, and percentiles answer a different question than this prediction does.

Frequently Asked Questions

How accurate is this prediction?

The mid-parental method is a rough family average, not a measurement. The ±8.5 cm band around the estimate is wide on purpose — it reflects how much siblings, nutrition, illness and timing of puberty can vary, and most children's adult height does land within a few inches of this kind of estimate. Published methods tuned on large datasets (like Khamis-Roche) can narrow the uncertainty somewhat, but nothing predicts an individual child precisely.

Can I use it to predict my own adult height as an adult?

No. This method only makes sense for a child whose final height is still ahead of them, and it requires the two parents' heights. If you are already grown, height is fixed — a calculator like a shoe-to-height estimator is guesswork by comparison, and growth plates have closed regardless.

Do growth supplements or steroids change the outcome?

No product you can buy makes bones grow longer. What can genuinely harm the outcome is medication that speeds up puberty — including anabolic steroids — because it closes the growth plates earlier and can lower adult height. Anything you are considering for a child should go through a pediatric endocrinologist first.

Is this medical advice?

No. This is general information, not a diagnosis or growth assessment. Concerns about a child's growth — falling off their own percentile line, or very early or late puberty — are conversations for a pediatrician, who can plot growth charts and, if needed, order a bone-age X-ray.

Is anything uploaded to a server?

No. The whole calculator is a few lines of vanilla JavaScript running in your browser. Your family's heights never leave your device — there is no account, no tracking and no network request attached to a calculation.