How to Use the Child Height Predictor
The mid-parental height formula is the most widely used statistical method for estimating a child's adult height from both parents' heights. For a son, it's (father's height + mother's height + 5.1 in) / 2; for a daughter, it's (father's height + mother's height - 5.1 in) / 2 — the roughly 5-inch adjustment accounts for the average height difference between men and women.
This calculator shows the predicted adult height along with a margin of about ±3.4 inches. That range reflects the fact that about 68% of children end up within it — genetics alone doesn't fully determine final height. Nutrition, sleep, physical activity, and chronic health conditions during childhood can meaningfully shift where a child lands within (or outside) that range.
Keep in mind this formula reflects average population trends and does not account for an individual child's bone age or hormone levels, so real outcomes can differ. This is a reference estimate, not a medical diagnosis. If your child's growth is noticeably faster or slower than peers, a pediatrician or pediatric endocrinologist can provide a proper evaluation and a more precise prediction based on growth charts and, if needed, a bone age X-ray.
Frequently Asked Questions
Genetics accounts for roughly 70-80% of a child's adult height, so the general trend is reasonably reliable. But nutrition, sleep, exercise, and overall health can shift the actual outcome within (or slightly beyond) the predicted margin of about ±3.4 inches.
If your child's growth rate is noticeably slower than peers, or a bone age X-ray raises concerns, see a pediatric endocrinologist regardless of what this calculator shows.