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Child Height Predictor

Predicts a child's adult height from both parents' heights using the mid-parental method, with the wide range that comes with it.

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In short Child Height Predictor is a free online tool on inputtesthub.com that predicts a child's adult height from both parents' heights using the mid-parental method, with the wide range that comes with it. It needs no account, no download and no payment, and there is no daily usage limit. Everything is processed inside your own browser, so the data you paste is never uploaded to a server.

How to use the Child Height Predictor

  1. Enter your figures in the input fields.
  2. The result updates as you type, together with the full working.
  3. Check the breakdown table to see exactly how the number was reached.

About the Child Height Predictor

The Child Height Predictor predicts a child's adult height from both parents' heights using the mid-parental method, with the wide range that comes with it. It runs as plain JavaScript inside the page, which means there is no upload step, no queue and no size limit imposed by a server — the only limit is your own device.

What people use it for

  • Getting a rough sense of where a child sits in the family range.
  • Understanding what a paediatrician means by "mid-parental target".
  • Settling a family argument about who a child takes after.

Details

Adjustment+6.5 cm boy, −6.5 cm girl
Prediction interval≈ ±8.5 cm
That is a 17 cm windowMost of the useful adult range
Genetics explains≈ 80% of adult height
The restNutrition, illness, puberty timing

The maths behind it

This tool uses average the two parents' heights, then add 6.5 cm for a boy or subtract 6.5 cm for a girl — half the 13 cm average difference between adult men and women. The prediction interval is about ±8.5 cm. Every intermediate value is shown on screen, so the result can be checked by hand.

The interval is the result, not a caveat on it. This method places a child within their family's range and does nothing more — bone-age imaging and serial measurements on a real growth chart are what clinicians use when the answer matters.

Where this tool stops

It assumes both biological parents' heights are known and that the child is healthy and adequately nourished. It cannot account for early or late puberty, chronic illness, or any of the conditions that affect growth — all of which are exactly the situations where someone would most want a prediction.

Frequently asked questions

How accurate is the mid-parental height method?
Not very, and it does not pretend to be. The ±8.5 cm interval means the honest answer is a 17 cm window, which covers most adult heights. It is useful for saying whether a child is broadly on track for their family, and useless for predicting a specific number.
My child is much shorter than their classmates — is that a problem?
Usually not by itself. Children grow at very different times and a late developer can look short right through the year their friends have a growth spurt. What actually matters is the trend on a growth chart: a child who has been steadily on the same centile is fine, and a child crossing downwards through centiles should see a paediatrician. Neither of those is something a formula with two numbers can see.
Do I need an account to use the Child Height Predictor?
There is no cost and no cap. The Child Height Predictor is not a demo of a paid product, so nothing is held back or watermarked.
Can you see what I put into this page?
No. The Child Height Predictor runs entirely in your browser using JavaScript. Nothing is transmitted, logged or stored, which you can verify yourself in the Network tab of your browser's developer tools.
What formula does the Child Height Predictor use?
It uses average the two parents' heights, then add 6.5 cm for a boy or subtract 6.5 cm for a girl — half the 13 cm average difference between adult men and women. The prediction interval is about ±8.5 cm. The full working is printed under the result, so you can follow every step rather than trusting a black box.
Who is the Child Height Predictor for?
Typical uses: getting a rough sense of where a child sits in the family range. Understanding what a paediatrician means by "mid-parental target". Settling a family argument about who a child takes after. It is built for exactly those cases rather than being a general-purpose tool with this bolted on.
When is the Child Height Predictor not the right tool?
It assumes both biological parents' heights are known and that the child is healthy and adequately nourished. It cannot account for early or late puberty, chronic illness, or any of the conditions that affect growth — all of which are exactly the situations where someone would most want a prediction. Knowing where a tool stops being trustworthy matters more than the cases where it works.
Which values should I know?
Adjustment is +6.5 cm boy, −6.5 cm girl. Prediction interval is ≈ ±8.5 cm. That is a 17 cm window is Most of the useful adult range. These are printed on the page itself, so you do not have to take them on trust.
Can I rely on this for exact work?
The calculation runs in double precision and the result is shown to ten significant figures, so converting a value and converting it back returns the original. What is displayed is rounded for readability; what is copied is not.

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