Height Predictor

You only need the two parents' heights. Measured heights are better than remembered ones, since people often overestimate by an inch or two.

1. Choose whether the Child is a Boy or a Girl. The formula adjusts for this.
2. Choose Units: Centimetres or Inches. If you switch, retype both heights afterward, because the boxes keep the numbers that were already in them. The defaults of 178 and 165 are centimeter values and would give an absurd result if read as inches.
3. Enter the Father's height.
4. Enter the Mother's height.
5. Read the predicted adult height at the top, followed by the average of the parents and the likely range.

The result is shown in the unit you chose, with the equivalent in feet and inches beside it. Use the same kind of measurement for both parents, ideally barefoot and standing straight, since a 2 cm difference in one parent shifts the estimate by 1 cm.

The mid-parental method averages the two parents' heights and then shifts the figure by 13 cm to reflect the typical difference between adult men and women:

Take a father of 178 cm and a mother of 165 cm. Their average is 171.5 cm, or 5 ft 7.5 in. For a boy, (178 + 165 + 13) / 2 gives 178.0 cm, which is 5 ft 10.1 in. For a girl, (178 + 165 - 13) / 2 gives 165.0 cm, about 5 ft 5 in.

The tool then shows a likely range of 8.5 cm either side, which is 3.3 inches. The boy in this example falls between 169.5 and 186.5 cm (5 ft 6.7 in to 6 ft 1.4 in), and the girl between 156.5 and 173.5 cm. In inches the same method works the same way: a father of 70 in and a mother of 64 in give a boy about 69.6 in (5 ft 9.6 in) and a girl about 64.4 in (5 ft 4.4 in). One inch is 2.54 cm, and the tool converts internally.

A range of 17 cm is wide on purpose. Children of the same parents, even siblings of the same sex, regularly end up several centimeters apart, and the formula describes the center of that spread, not a promise.

Both parents count equally, so raising one parent by 6 cm raises the estimate by 3 cm. The method has no way to tell a family where both parents are tall from one where a single parent is very tall, because it only uses the average.

The formula uses only the parents' heights. It says nothing about the child's current height, growth percentile or pace of growth, and it cannot account for nutrition, illness, the timing of puberty or the parents' own family background. A child who is tall at age 8 may stop growing earlier than a late developer who is small at that age. Parents who grew up with poor nutrition or who were measured at different ages can also skew the result. Step-parents and adoptive parents do not pass on their height genetically, so the formula only makes sense for biological parents.

The range is the useful part. A boy predicted at 178.0 cm has a plausible adult height anywhere from about 169.5 to 186.5 cm, and many children finish near the middle, though that is a tendency and not a rule.

Treat the output as a conversation piece and not a target. It is an estimate for general information and not a medical assessment or diagnosis. A pediatrician plots measurements on growth charts over time and is the right person to judge whether a child is growing as expected, so if you have a concern about growth, ask them rather than relying on a formula.

Once you have a figure, you may want it in another unit. Try the centimeters to feet converter, the feet to centimeters converter or the inches to centimeters converter. For health context, the BMI calculator and the ideal weight calculator both use height as an input, and the age calculator gives a child's exact age in years, months and days.