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Mid-Parental Height Calculator: Estimating a Child's Adult Height

A child's eventual adult height is heavily influenced by both parents' heights, and a simple formula gives a rough statistical estimate of where it might land.

For boys: (mother's height + father's height + 13 cm) Γ· 2

Add both parents' heights in centimeters, add 13 cm (about 5 inches, an average adjustment for the male-female height gap), then divide by 2.

For girls: (mother's height + father's height βˆ’ 13 cm) Γ· 2

Same calculation but subtracting 13 cm instead of adding it, reflecting that girls, on average, end up shorter than boys from the same two parents.

The result comes with roughly an 8-10 cm margin of error

This formula gives a midpoint estimate, not a precise number β€” the actual adult height typically falls within about 8-10 cm (roughly 3-4 inches) above or below the calculated figure, reflecting normal genetic and environmental variation.

Genetics sets a range, not a fixed outcome

Parental height accounts for a large share of the variation in adult height, but nutrition, sleep, chronic illness, and overall health during childhood and adolescence all influence where within that genetic range a child actually lands.

This is a statistical estimate, not a growth diagnosis

This formula is a rough population-level estimate for curiosity or general planning. It is not a substitute for a pediatrician tracking a child's actual growth curve over time, which is the real way to catch a genuine growth concern.

Where the mid-parental height formula comes from

The formula is a simplified version of research correlating parental height with the average adult height of their children across large populations. It works reasonably well as a group-level average, but any individual child can land meaningfully outside the estimated range due to normal biological variation.

Why a growth chart matters more than a one-time formula

A pediatrician tracking a child's height and growth velocity over years on a standardized growth chart gets far more useful information than a single mid-parental height calculation, since a child's own growth trajectory over time reveals far more than a static estimate based only on parental height.

Frequently Asked Questions

How accurate is the mid-parental height formula?

It is a reasonable population-level estimate, but individual results vary by roughly 8-10 cm in either direction. It should be treated as a rough ballpark, not a precise prediction of your child's actual future height.

Should I be concerned if my child seems shorter than the formula predicts?

Not necessarily β€” normal variation alone explains most differences from this estimate. If you have genuine concerns about a child's growth pattern, a pediatrician tracking growth velocity over time is the appropriate way to evaluate it, not this formula.