Child Height Predictor · Practical guide
How Tall Will My Child Be?
Parents' heights predict a child's adult height within about 2 inches — here's the formula and a worked example.
At a glance
The short answer
The most widely used estimate is the mid-parental height method: for a boy, add the mother's and father's heights, add 5 inches, and divide by 2; for a girl, subtract 5 inches instead. The result is the child's target adult height, with a typical range of plus or minus 2 inches. With a 5'5" (65 in) mother and a 5'10" (70 in) father, a boy is predicted to reach 5'10" (70 in), most likely ending up between 5'8" and 6'0".
Interactive tool
Child Height Predictor
Enter your own values, then compare the result with the examples below.
Predicted Adult Height
Worked example for a boy and a girl
Same parents, different formula constant. For their son: (65 + 70 + 5) ÷ 2 = 70 inches, or 5'10", with a likely range of 68-72 inches. For their daughter: (65 + 70 − 5) ÷ 2 = 65 inches, or 5'5", with a likely range of 63-67 inches. The 5-inch adjustment accounts for the average height difference between adult men and women.
What the predictor above adds
Enter the child's current height and age along with both parents' heights, and the calculator also approximates a growth percentile — how your child's current height compares to CDC growth chart medians for their age and gender. A child tracking along the 75th percentile who stays on that curve will usually land at the higher end of the predicted range.
How much faith to put in the number
Genetics explains roughly 80% of height, and the mid-parental method captures the biggest piece of that. Nutrition, sleep, overall health, and the timing of puberty explain most of the rest. Treat the prediction as a realistic target zone, not a promise — about two-thirds of children finish within the 2-inch range the calculator shows.
Frequently Asked Questions
How accurate is a child height prediction?
The mid-parental method is typically accurate within about 2 inches (5 cm) for most children. Nutrition, health, and puberty timing can shift the final result in either direction.
Can I predict height if I only know one parent's height?
The mid-parental formula requires both parents' heights to work. A single parent's height alone is not a reliable predictor since children inherit a mix from both sides.
When do boys and girls stop growing?
Girls typically reach adult height by 14-15, about two years after starting puberty. Boys usually keep growing until 16-17, sometimes into their late teens.
Does the doubling-a-2-year-old's-height trick work?
Doubling a child's height at age 2 is a popular rough rule and lands surprisingly close for many kids, but the mid-parental formula used here is more consistent because it accounts for the parents' actual heights.