Height Calculator — predict a child's adult height

This is an estimate, not a guarantee. Height depends on genetics beyond the parents, plus nutrition, sleep, health and puberty timing, so a real adult height can fall outside the range. For any concern about a child's growth, follow their growth chart with a pediatrician.

How it works

The mid-parental (target) height method predicts a child's adult height from the two biological parents' heights. Take the average of the parents and shift it for the child's sex (because adult men are about 13 cm taller than women on average):

• Boy: (father's height + mother's height + 13 cm) ÷ 2
• Girl: (father's height + mother's height − 13 cm) ÷ 2

The result is a target, reported with a range of about ±10 cm (±2 standard deviations) — the band that covers roughly 95% of children. It has been used to assess children's growth since the method was first described in 1970.

Worked example

A father of 178 cm and a mother of 165 cm:

• Average of the parents: (178 + 165) ÷ 2 = 171.5 cm
• Boy: 171.5 + 6.5 = 178 cm (likely range 168–188 cm)
• Girl: 171.5 − 6.5 = 165 cm (likely range 155–175 cm)

Frequently asked questions

How accurate is a mid-parental height prediction?

It's a guide, not a promise. The method reports the target with a range of **±10 cm (±2 standard deviations)** — the band that covers roughly 95% of children — so an individual child can still land anywhere in (or occasionally outside) that wide window. A child's own height-for-age percentile, tracked over time, predicts better than the parents' heights alone.

Why is there a 13 cm (about 5 inch) adjustment?

Because adult men are on average about 13 cm taller than adult women. Adding it for boys and subtracting it for girls shifts the parents' average onto the child's expected adult scale.

Can it predict height at a specific age?

No — mid-parental height estimates **final adult** height, not height at age 5 or 10. To see where a child sits for their age right now, use a height-percentile calculator against growth charts.

What else affects how tall a child becomes?

Genetics beyond the two parents, nutrition, sleep, general health, and the timing of puberty all matter. Chronic illness or hormonal conditions can shift growth, which is why persistent concerns are worth raising with a clinician.

Does the calculator work in inches?

Yes — switch the height units to inches and enter the parents' heights that way; the prediction and range are shown in the same unit.

My child is already taller than the prediction — is that a problem?

Not on its own. The prediction is a central estimate with a wide range, and children who are tracking healthily along their own percentile are usually fine. A sudden change in the growth curve is more worth discussing with a pediatrician than a steady position above or below the target.