What is the mid-parental height formula?

For boys: add both parents' heights in cm, add 13 cm, then divide by 2. For girls: add both parents' heights, subtract 13 cm, then divide by 2. The 13 cm adjustment accounts for the average height difference between adult males and females.

What does the ±2 SD range mean?

Approximately 95% of children with a given parental height combination will reach an adult height within ±2 standard deviations of the mid-parental target. One SD is roughly 4.25 cm (1.67 in), so the ±2 SD range spans about ±8.5 cm (±3.35 in) around the target.

How accurate is this prediction?

Mid-parental height explains roughly 60–80% of the variance in adult height. It is a useful clinical screening tool, not a precise forecast. Nutrition, health status, timing of puberty, and other factors can shift a child's final height inside or outside the predicted range.

At what age is the prediction most relevant?

The target height applies once the child has completed growth — typically age 18–21 in boys and 16–18 in girls. During childhood, doctors compare current height to age- and sex-specific percentiles, then use the mid-parental target to judge whether growth is tracking toward the genetic potential.

Does birth order or nutrition affect the result?

This calculator uses only parental heights. Nutrition, general health, sleep, and other environmental factors can push a child toward the upper or lower end of the predicted range. Optimal conditions tend to favor reaching the higher end.

Should I use this for a medical decision?

This tool is for informational purposes only. If you have concerns about your child's growth — especially if they are tracking significantly below the lower end of the predicted range — consult a pediatrician or pediatric endocrinologist for a full clinical evaluation.

Mid-Parental Height Calculator

Enter both parents' heights and the child's sex to get a predicted adult height with a ±2 SD genetic range in both metric and imperial.

Parent & Child Data

Height Unit

Child's Sex

Father's Height

Mother's Height

Enter parent heights and child's sex, then click Calculate.

Summary

The Mid-Parental Height Calculator uses the standard clinical formula — averaging both parents' heights with a ±6.5 cm sex correction — to estimate a child's adult target height. Results include the ±2 standard deviation range (±8.5 cm / ±3.35 in) that captures roughly 95% of children with those parental heights. Output is shown in both centimeters and feet/inches. This tool reflects the method used in pediatric practice for comparing a child's growth trajectory to their genetic potential.

How it works

Select the child's sex (boy or girl).
Enter the father's height in centimeters or feet and inches.
Enter the mother's height in the same unit.
Click "Calculate" to see the predicted adult height.
Review the ±2 SD range — roughly 95% of children with these parents will fall within this window.

Use cases

Estimate a child's genetic height potential based on parental heights.
Help parents understand whether a child's current growth trajectory aligns with expectations.
Assist pediatricians in counseling families about height and growth concerns.
Compare a child's measured height to the predicted target for clinical context.
Evaluate whether growth hormone therapy goals are realistic for a given child.
Screen for disproportionate short or tall stature relative to family background.

Frequently Asked Questions

Last updated: 2026-06-18 · Reviewed by Nham Vu