Child Height Predictor

Predicting Adult Height from Parental Heights

This calculator uses the mid-parental height method, the most widely cited clinical formula for estimating a child's adult height based on the heights of both biological parents. For boys, the predicted height equals (mother's height + father's height + 5 inches) / 2. For girls, it equals (mother's height + father's height - 5 inches) / 2. The 5-inch adjustment accounts for the average height difference between males and females. Results fall within a range of plus or minus 2 inches in most cases, reflecting the natural variation in genetic expression.

Genetics accounts for approximately 60-80% of a person's adult height, with the remainder influenced by nutrition, health during childhood, sleep quality, and physical activity. Children who experience chronic malnutrition, untreated growth hormone deficiency, or prolonged illness may not reach their genetic height potential. Conversely, children with excellent nutrition in developed countries are trending taller than their parents' generation. Pediatricians track height on CDC growth percentile charts from ages 2 to 20, and a child who consistently follows the 50th percentile is expected to reach roughly the average adult height for their sex.

The mid-parental height formula provides a useful estimate but has limitations. It assumes both parents reached their full genetic height potential and that the child will grow up in similar nutritional and health conditions. Children with one very tall and one very short parent may not average neatly between them due to dominant gene expression. For more precise predictions, pediatric endocrinologists use bone age X-rays of the left hand and wrist (the Greulich-Pyle method), which assess skeletal maturity and remaining growth potential. This clinical approach is especially useful for children who are growing faster or slower than expected.