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Child Height Predictor
Use this free child height predictor to estimate how tall your child will grow. Enter the mother's and father's heights and the child's sex, and it predicts adult height with the mid-parental height method — the parents' average, plus 6.5 cm for a boy or minus 6.5 cm for a girl — with a likely range of ±8.5 cm.
Heights in feet and inches: 5 ft 5 in is 165 cm, 5 ft 11 in is 180 cm. Multiply inches by 2.54 to get centimetres.
Predicted height range
Bars compare the parents' heights with the predicted adult height. The likely range covers most children, but not every child.
How it works
Parents ask the same question in every generation: how tall will my child grow up to be? This child height predictor gives a reasoned estimate from the one factor that matters most — the heights of the parents. It uses the mid-parental height method, the approach pediatricians have used for decades, and it shows a range rather than a single magic number, because real children vary.
The method starts by averaging the two parents' heights. That average is called the mid-parental height, and it is the best single summary of the height genes a child inherits — half from each parent. Then it adjusts for sex, because on average adult men are about 13 cm taller than adult women. A boy's predicted height adds 6.5 cm to the mid-parental height, and a girl's subtracts 6.5 cm. That 6.5 cm is simply half of the average 13 cm difference between adult men and women.
Boy: predicted height = mid-parental height + 6.5 cm
Girl: predicted height = mid-parental height − 6.5 cm
The result is a target height, not a promise. Most children — roughly 9 out of 10 — end up within 8.5 cm above or below that target, which is why the calculator shows a likely range of ±8.5 cm. A child landing anywhere in that range is growing exactly as the family pattern would suggest. Only a child who falls well outside the range, or whose growth suddenly slows or speeds up, is a reason to ask a pediatrician to take a closer look.
Genetics sets the range, but it is not the whole story. Nutrition, sleep, illness, and general health during childhood all nudge a child toward the top or the bottom of their inherited range. A child who eats well, sleeps enough, and stays healthy through childhood is more likely to reach the upper part of their range, while long illness or poor nutrition can hold growth back. That is also why this method works best as a family guide rather than a medical test: it describes what is typical for children with these parents, and it cannot see the individual details of one child's health.
This page also answers the searches for "height predictor calculator" and "child height calculator" — they are the same tool with different names, so there is no need for a separate page. The method, the formula, and the ±8.5 cm range are identical whichever name you arrived by. If you prefer feet and inches, switch the display unit and the calculator converts: centimetres divided by 2.54 gives inches, and 12 inches make a foot, so 179 cm becomes 70.5 inches, or 5 feet 10.5 inches.
One more thing worth knowing: children do not grow in a straight line. They grow fastest as babies, slow down through childhood, then shoot up again in the teenage growth spurt — girls usually between 10 and 14, boys between 12 and 16. A child who is short at eight can still reach a tall predicted height if their spurt comes late, and a tall ten-year-old can end up average if their spurt comes early and finishes early. The predictor ignores all of that timing and looks only at the final adult height, which is why it is most useful as a long-range guide, not as a judgment on how a child is doing right now.
Worked example
Take a mother who is 165 cm tall (5 ft 5 in) and a father who is 180 cm tall (5 ft 11 in), and a son. Here is exactly what the calculator does.
Step 1 — Mid-parental height. Add the parents' heights and divide by two: (165 + 180) ÷ 2 = 345 ÷ 2 = 172.5 cm.
Step 2 — Adjust for a boy. Add 6.5 cm: 172.5 + 6.5 = 179 cm. That is the predicted adult height — about 5 ft 10.5 in.
Step 3 — The likely range. Subtract and add 8.5 cm: 179 − 8.5 = 170.5 cm and 179 + 8.5 = 187.5 cm. Most boys with these parents end up between 5 ft 7 in and 6 ft 2 in.
Step 4 — For a girl with the same parents, subtract instead: 172.5 − 6.5 = 166 cm (about 5 ft 5.5 in), with a likely range of 157.5 to 174.5 cm.
Enter the same numbers — mother 165 cm, father 180 cm, boy — and the tool shows exactly these results, with the chart comparing the parents' heights against the 179 cm prediction.
FAQ
How accurate is the mid-parental height method?
It is accurate as a family guide, not as a precise forecast. About 9 in 10 children end up within 8.5 cm of the predicted height, which is why the calculator shows a range. It cannot account for individual nutrition, illness, or the timing of the teenage growth spurt, so treat the single number as the middle of a range, not a promise.
Why do boys add 6.5 cm and girls subtract 6.5 cm?
Adult men are on average about 13 cm taller than adult women, so the method splits that difference in half. A boy gets half the difference added to the parents' average height, and a girl gets half subtracted. The 13 cm figure is a population average, and it is the same reason the two predictions for one family differ by exactly 13 cm.
Does this work for adopted children?
No, not in the usual way. The method assumes the child inherits height genes from the two adults entered, so it needs the biological parents' heights. For an adopted child, use the biological parents' heights if they are known; the heights of adoptive parents describe the home, not the genes.
My child is much shorter than the prediction. Should I worry?
One measurement is rarely a reason to worry, especially if your child is growing steadily along their own curve. But if your child is well below the predicted range, has stopped growing, or has dropped across growth-chart lines, it is worth mentioning to a pediatrician, who can check growth history, nutrition, and hormones.
Can nutrition or sleep change my child's adult height?
They can shift a child within their inherited range, but they cannot rewrite it. Good nutrition, enough sleep, and staying healthy help a child reach the upper part of their range, while long illness or poor nutrition can hold growth back. No food, supplement, or exercise has been shown to push a child beyond what their genes allow.