A childās expected adult height is the average of both parentsā heights plus 6.5 cm for a boy or minus 6.5 cm for a girl. A father of 182 cm and a mother of 168 cm are expected to have a son of about 181 cm, give or take roughly 8.5 cm.
How do you predict a childās adult height?
The best known method is the mid-parental height, or target height. Add the heights of both parents, add 13 cm for a boy or subtract 13 cm for a girl, and divide by two. For a father of 182 cm and a mother of 168 cm, a boy is expected to reach (182 + 168 + 13) Ć· 2 = 181.5 cm and a girl (182 + 168 ā 13) Ć· 2 = 168.5 cm. The 13 cm is the average height difference between adult men and women.
How accurate is the prediction?
Genetics explains around 80% of the variation in height, but the formula gives only an average. Siblings in one family can differ widely. About 95% of children end up within roughly 8.5 cm of their target height, so for a prediction of 181 cm the real result is most likely between 173 and 190 cm. Nutrition, sleep, health, the timing of puberty and chance account for the rest. Dutch adults are among the tallest in the world: men average around 183 cm and women around 170 cm.
Growth charts and when to ask a doctor
Child-health clinics plot a childās height on a growth chart. The pattern matters more than one measurement: a child who stays in the same percentile band is usually growing well. A clear drop across several measurements, a height far below the target range or very early or late puberty are good reasons to talk to a GP or paediatrician.
What influences growth?
- Nutrition: enough energy, protein and calcium. Adults can check their own needs with the Protein Calculator.
- Sleep: growth hormone is mostly released during deep sleep.
- Puberty timing: early developers grow sooner but do not always end taller.
- Health conditions: thyroid problems, coeliac disease and growth hormone deficiency can slow growth.
The calorie estimates in the Calorie Calculator are for adults only, as childrenās needs are assessed by a doctor or dietitian. Parents tracking family planning may also like the Period Calculator.
How to use this calculator
- Enter the fatherās and motherās heights in centimetres.
- Choose whether the child is a boy or a girl.
- Press Calculate to see the predicted adult height and the likely range.
- Compare with your childās growth chart at the child-health clinic for a personal picture.
Key figures at a glance
| Boy | (father + mother + 13) Ć· 2 |
|---|---|
| Girl | (father + mother ā 13) Ć· 2 |
| Margin | Ā± 8.5 cm (about 95%) |
| Genetic share | around 80% |
Frequently asked questions
Add both parentsā heights, add 13 cm and divide by two. Expect a margin of about 8.5 cm either way.
Add both parentsā heights, subtract 13 cm and divide by two.
No. It is an average, and children can end up more than 8 cm above or below the target.
Girls usually around age 15 to 16 and boys around 17 to 18, sometimes a little later.
If your child drops across growth-chart lines, is far below the target height or has very early or late puberty.