Child height predictor: a height calculator from parents' heights

Enter the heights of a child's mother and father to estimate how tall the child is likely to be as an adult. The calculator uses the mid-parental height method that doctors have used since Tanner described it in 1970, and shows the range most children fall within. It is a family estimate, not a medical prediction.

Quick answer

For a boy, add 13 cm to the mother's height, add the father's height and divide by two; for a girl, subtract 13 cm instead. With a father of 178 cm and a mother of 165 cm, a son's estimated adult height is 178 cm and a daughter's 165 cm. Tanner suggested most children end up within about 8.5 cm either side of this figure.

Based on Wright & Cheetham 1999, Arch Dis Child (mid-parental height) · Page updated 19 October 2026

Your child

GirlBoy

Units

cmft, in

Father's height (cm)

Mother's height (cm)

Use the biological parents' heights, measured without shoes if you can. Self-reported heights are often a little too high.

Enter both parents' heights to see the estimate.

An estimate from parents' heights only, not a medical prediction or diagnosis. If you are worried about how your child is growing, see your doctor, who will measure your child and use a growth chart.

How to use the Child Height Predictor

Choose whether the child is a boy or a girl, and your units.
Enter the biological father's height and the biological mother's height, measured without shoes if possible.
Read the estimated adult height and the usual range around it.
Save the estimate if you like. If you are worried about your child's growth, take it to your doctor along with your child's own measurements.

How the mid-parental height method works

Children's adult height depends strongly on their parents' heights, and doctors use that link every day. In 1970 Tanner and colleagues published growth standards that allowed for parents' heights, with a simple rule that is still in use: average the two parents' heights after adjusting one of them for the usual difference between men and women. For a boy, add 13 cm to the mother's height before averaging with the father's; for a girl, take 13 cm off the father's height before averaging with the mother's. The result is called the mid-parental height or target height. It works the same in feet and inches, where 13 cm is about 5 inches.

What the ±8.5 cm range means

Tanner suggested that a child's adult height would usually fall within 8.5 cm of the mid-parental height, which is roughly two standard deviations either side. That is a wide band: 17 cm from bottom to top. Some newer British charts use about 10 cm, and the Royal College of Paediatrics and Child Health's charts, which use a refined version of the method, say four children out of five end up within 7 cm of the target. The calculator shows Tanner's ±8.5 cm because it belongs to the same formula, but the exact edges matter less than the message: brothers and sisters of the same parents can end up quite different heights.

Why it is only an estimate

The formula only knows the parents' heights. It cannot see illness, nutrition, hormones or the timing of puberty, and it has known weak points. Children of very tall or very short parents tend to be less extreme than their parents, an effect called regression to the mean, so the simple formula can overestimate the height of children of very tall parents and underestimate it for very short parents. Reported heights are often wrong: a 2025 review in BMC Pediatrics notes that parents tend to overestimate their height, fathers more than mothers. The formula was also developed in England, and later studies in other countries have proposed their own versions, partly because children grow taller than their parents' generation when living conditions improve.

How doctors use mid-parental height

Doctors do not use the target height to predict an exact number. They compare a child's current height on a growth chart with where the parents' heights would place them, to see whether the child is growing as expected for the family. The Royal College of Paediatrics and Child Health says further assessment is needed, for example, when a child's height centile is more than three centile spaces below the mid-parental centile, or when a child's height drops by more than two centile spaces. A short child of short parents is often simply following the family pattern; a child whose growth slows, or who is far below that pattern, should be checked.

Measuring the parents and the child

Measure each parent barefoot, standing straight with heels against a wall, and mark the top of the head with a flat object held level. For the child, a doctor or nurse will measure with proper equipment: a lying length board up to age two and a wall-mounted measure after that, as the British guide for family doctors describes. A single measurement says little; a few measurements 6 to 12 months apart show the growth rate, which doctors use to judge growth. If you have questions about your baby before birth, the pregnancy calculator gives due dates, and the BMI calculator covers adults.

Frequently asked questions

How tall will my child be?

A child height predictor or height calculator based on parents' heights gives a likely figure and a range. Add the parents' heights, add 13 cm for a boy or take away 13 cm for a girl, and divide by two; most children end up within about 8.5 cm of that number.

How accurate is the mid-parental height formula?

It is a rough guide. The range around the result is about 17 cm wide, children of very tall or very short parents usually end up closer to average, and illness, nutrition and puberty timing are not included.

Can I use it with only one parent's height, or for an adopted child?

No. The method needs the heights of both biological parents, because it relies on the family link between parents' and children's heights.

My child is shorter than the predicted range. Should I worry?

Not necessarily, but see your doctor, who can measure your child over time on a growth chart. Doctors look more closely when a child is far below the family pattern or when growth slows down.

Why is 13 cm added or subtracted?

To allow for the usual difference in adult height between men and women, so that the mother's and father's heights can be averaged for a child of either sex. It is the adjustment in Tanner's 1970 method; some charts use 14 cm.