Child Height Predictor
A genetic target range from both parents’ heights — the Tanner mid-parental formula with its ±5 cm band.
How to use
- Enter the father’s and mother’s heights in centimeters.
- Pick the child’s sex.
- The target height and typical range appear instantly.
Frequently asked questions
How does the mid-parental height method work?
It averages the parents’ heights, then shifts by the sex difference: boys get +6.5 cm, girls −6.5 cm. This is the classic Tanner mid-parental formula, still used in pediatrics as a rough target zone.
Why is the range ±5 cm?
Genetics set a range, not a point: environment (nutrition, sleep, illness) moves the outcome within roughly two standard deviations of the target, which the formula rounds to ±5 cm. Most children land inside it; some healthy children do not.
Can a child end up taller than both parents?
Yes. If nutrition and health improved between generations, children commonly exceed the mid-parental target — the formula assumes parents measured as adults in similar conditions.
When should growth be checked by a doctor?
When growth velocity looks off: crossing percentile lines on a growth chart, growing less than ~5 cm/year between ages 4 and puberty, or falling outside the predicted range plus family pattern. Height potential is one input — growth *rate* is the more urgent signal.
Do the parents’ heights need any correction?
Measure both parents in centimeters as adults. If only estimates exist (or one parent’s height is unknown), the result degrades — this is a two-parent formula by construction.