Height Predictor Calculator
Estimate a child’s adult height from parental heights using the mid-parental-height method, with metric and imperial results.
Enter your values
Change any assumption and calculate again to compare results.
What the mid-parental method estimates
The mid-parental-height method uses the biological parents’ heights to estimate a central adult-height target for a child. It is a population-based rule of thumb, not a prediction of an exact final height.
For boys, the traditional formula adds about 5 inches to the mother’s height, averages that with the father’s height and divides by two. For girls, it subtracts about 5 inches from the father’s height before averaging. The calculator performs the equivalent calculation in centimetres when metric units are selected.
Why a range is more useful than one number
Genes account for much of height variation, but nutrition, chronic illness, hormones, sleep, puberty timing and random genetic inheritance also matter. Even siblings with the same parents can end up at different adult heights.
The result therefore includes an approximate range of ±4 inches, or about ±10 cm, around the mid-parental estimate. That range is still not a medical guarantee.
When growth concerns need professional assessment
A height predictor cannot evaluate growth velocity, bone age, puberty stage or endocrine conditions. If a child is crossing growth percentiles rapidly, has unusually early or late puberty, or there is concern about growth, a pediatric professional can review the full growth chart.
Use this calculator as a simple family-height estimate rather than a diagnostic tool.
Important information
This calculator is for general education and planning. It is not a diagnosis, medical device or substitute for individualized healthcare advice. Measurements and formula estimates can differ from clinical assessments.
If the result could affect treatment, pregnancy care, medication, driving, military status or another safety-sensitive decision, confirm it with the appropriate qualified professional or official process.
Frequently Asked Questions
Is the predicted height exact?
No. It is a rough genetic estimate and actual adult height can be outside the displayed range.
Why does the formula use 5 inches?
The traditional mid-parental method adjusts for the average sex difference in adult height before averaging parental heights.
Can I enter centimetres?
Yes. Choose centimetres and the calculator converts internally and returns both metric and imperial results.