Child Height Predictor
Predict a child's adult height from the parents' heights with the mid-parental height method. A rough genetic estimate shown with a ±2 inch range.
How tall will my child be? Pediatricians answer that with the mid-parental height method: average the parents' heights, adjust for the child's sex, and expect the result within about two inches. This calculator does that math instantly and shows the prediction in inches and centimeters — with the honest caveat that genes are only part of the story.
How to use this calculator
- Enter the father's adult height in inches.
- Enter the mother's adult height in inches.
- Select whether the child is a boy or a girl.
- Click Calculate to see the predicted adult height with its expected range, in inches and centimeters.
The formula
Mid-parental height (Tanner method): boy = (father + mother + 5) / 2; girl = (father + mother − 5) / 2, all in inches. Expected range = prediction ± 2 inches.
Worked example
A boy whose father is 6'0" (72 in) and mother is 5'5" (65 in) has a predicted adult height of 71 inches (5'11"), with an expected range of 69–73 inches. A girl with the same parents would be predicted at 66 inches (5'6"), ranging 64–68.
Frequently Asked Questions
How does the mid-parental height method work?
It's simple arithmetic pediatricians have used for decades: add the parents' heights together, add 5 inches for a boy or subtract 5 inches for a girl, and divide by two. The result is the predicted adult height, and most children end up within 2 inches of it. The ±5 inch adjustment accounts for the average height difference between adult men and women.
How accurate is this prediction?
Roughly right, not precisely right. About 90% of children reach an adult height within 2 inches of the mid-parental prediction, which is why the calculator shows a range rather than a single number. The misses come from everything genes don't capture: nutrition, illness, sleep, and the random shuffle of which genes each child inherits. Treat it as a ballpark, not a destiny.
What else besides genetics affects final height?
Plenty. Good nutrition in childhood — especially enough protein, calcium, and vitamin D — lets a child reach their genetic potential, while chronic malnutrition or serious illness can hold them back. Sleep matters because growth hormone is released mainly during deep sleep. And timing varies: early or late puberty shifts when growth happens without necessarily changing the final height.
When do children stop growing taller?
Girls typically stop growing around 14–15, about two years after their first period, while boys usually continue until 16–17. Growth plates in the long bones fuse at the end of puberty, and no natural process reopens them afterward. If a teenager's growth seems far off the predicted track — much shorter, or still growing rapidly past 18 — a pediatrician can check growth charts and, if needed, bone age.
Can I use this before my child is born?
Yes — the method only needs the parents' heights and the child's sex, so it works as a fun estimate during pregnancy too. Just remember it's a population-average formula applied to one individual: your child's actual height will depend on the specific mix of genes they inherit plus their environment growing up.