Tanner 1970

Mid-Parental Height Calculator

Target adult height from the biological parents' heights, with the ±8.5 cm expected range and the CDC stature percentile of the target at 20 years.

Parental Heights

Switching converts what you have already typed.
Adds 13 cm for boys, subtracts 13 cm for girls.
120–220 cm
120–220 cm

Use measured biological-parent heights where possible. Self-reported heights are typically over-reported, which shifts the target upward.

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Frequently Asked Questions About Mid-Parental (Target) Height

Tanner, Goldstein and Whitehouse (1970) average the two biological parents' heights and correct for the child's sex: boys = (father + mother + 13) / 2 and girls = (father + mother − 13) / 2, in centimetres. The equivalent form is the parents' average plus 6.5 cm for a boy or minus 6.5 cm for a girl, which is the wording used by references such as StatPearls.

The 13 cm constant approximates the average adult height difference between men and women at the same percentile (reported as about 13.2 cm in a 2025 BMC Pediatrics review of the formula).

Tanner's method reports the target height with a range of about ±8.5 cm, roughly two standard deviations of the within-family spread of adult height, and that is the value this calculator uses. Published widths for the same formula differ: StatPearls states that expected adult height usually falls within 8 cm of the mid-parental height, and a population-specific alternative (Ogata 1990, Japan) reports ±9 cm for boys and ±8 cm for girls.

The band is a range for adult height given these parents' heights, not a percentile band on the growth chart. It should not be quoted alongside a chart percentile as if the two were the same scale.

It places the single target-height number on the CDC 2000 stature-for-age chart at 240 months (20 years, the oldest age on the 2–20 year chart), using the same LMS transform the growth calculator uses: z = ((X / M)L − 1) / (L × S). It answers "how tall is this family's target compared with all 20-year-olds of that sex", which is useful when the child's own height percentile sits far from the family's.

It is a population percentile, so it is not interchangeable with the ±8.5 cm range. Target height is also not a prediction for an individual child: a child tracking well below the target range warrants a growth assessment rather than reassurance from this number alone.