Child Height Predictor

How tall will your child grow to be? Nothing about height is guaranteed, but genetics give a strong starting point, since roughly 80% of a person's adult height is inherited. This calculator uses the Mid-Parental Height method, a simple technique drawn from decades of paediatric growth research and used by doctors around the world as a first estimate of a child's likely adult stature. You enter both parents' heights and the child's sex, and it returns a predicted adult height in centimetres and feet/inches, along with the range most children actually land in.

Not medical advice. This is a screening and educational tool, not a diagnosis or a promise. A child's growth depends on many factors beyond the parents' heights, and the estimate carries a wide margin. If you have any concern about your child growing too slowly or too quickly, or falling off their growth curve, please consult a paediatrician or paediatric endocrinologist rather than relying on an online figure.

Who this calculator is for

It is aimed at parents who are simply curious about how tall their child might become, families tracking a youngster's growth between health check-ups, and anyone who wants to understand the genetics of height. It works best for healthy children growing along a normal curve. It is not designed for children with growth disorders, hormonal conditions or chronic illness affecting growth, whose height should be assessed clinically.

The Mid-Parental Height method

The formula is straightforward. For boys: Predicted Height = (Father's Height + Mother's Height) / 2 + 6.5 cm. For girls: Predicted Height = (Father's Height + Mother's Height) / 2 − 6.5 cm. The 6.5 cm adjustment reflects the average height difference between adult men and women. The ±8.5 cm range shown with the result represents about one standard deviation, meaning roughly 68% of children with the same parents end up within that window; the rest fall a little outside it in either direction.

Other methods and how they differ

The Mid-Parental method only needs parental heights, which is why it is so widely used. More involved approaches such as the Khamis-Roche method add the child's current age, height and weight to the parents' heights to refine the estimate without needing an X-ray, while clinics also use bone-age assessments (a hand and wrist X-ray) to judge how much growth remains from the maturity of the growth plates. These can be more precise for an individual child but require measurements this quick tool does not collect.

Worked example

Imagine a father who is 178 cm and a mother who is 165 cm, with a son. The mid-parental height is (178 + 165) / 2 = 171.5 cm. Adding the 6.5 cm boy adjustment gives a predicted adult height of 178 cm, or about 5 feet 10 inches. The expected range is roughly 169.5 cm to 186.5 cm, so while 178 cm is the central estimate, a final height anywhere across that span would be entirely normal for this child.

Other factors that influence height

Beyond genetics, several things shape final height: nutrition (enough protein, calcium, zinc and vitamin D during the growing years), sleep (growth hormone is released mainly during deep sleep), physical activity (regular moderate exercise supports healthy growth), and overall health (chronic illness or untreated conditions can slow growth). Timing matters too: early puberty tends to limit final height, while later puberty often allows more time to grow taller.

Tips and common mistakes

• Measure both parents accurately, standing straight without shoes, since small errors feed straight into the prediction.
• Treat the result as a range, not a single fixed number; the ±8.5 cm window is the realistic picture.
• Do not use the boy formula for a girl or vice versa, as the 6.5 cm adjustment is reversed for each.
• Remember the estimate predicts adult height, not how tall the child should be at their current age.
• If a child consistently tracks well outside the predicted range, see a paediatrician rather than re-running the numbers.