How this child height predictor works
This tool estimates a child's adult height using the mid-parental method, a simple and widely used rule of thumb. The idea is that a child's height is strongly influenced by their parents, so the parents' heights give a reasonable starting point for a prediction.
The calculation has two steps. First, it finds the mid-parental height — the average of the mother's and father's heights: (mother + father) ÷ 2. Second, it adjusts for the child's sex, because adult men are on average taller than adult women: for a boy it adds 6.5 cm (about 2.6 in), and for a girl it subtracts 6.5 cm. The result is a midpoint, and most children fall within roughly ±8.5 cm (±3.3 in) of it — the typical expected range.
Reference note: imperial heights are converted to metric before the formula runs — total height in inches is multiplied by 2.54 to get centimetres. The ±8.5 cm range is an approximation of the spread seen around the mid-parental prediction. This is an informational estimate for fun and curiosity, not medical advice; genetics and nutrition vary, so consult a pediatrician about any real concern.
Mid-parental method at a glance
| Step | Formula |
|---|---|
| Mid-parental height | (mother's height + father's height) ÷ 2 |
| Boy's predicted height | mid-parental height + 6.5 cm |
| Girl's predicted height | mid-parental height − 6.5 cm |
| Typical range | prediction ± 8.5 cm (± 3.3 in) |
Frequently asked questions
- How tall will my child be?
- No one can know for certain, but the mid-parental method gives a useful estimate. Average the mother's and father's heights, then add 6.5 cm (about 2.6 in) for a boy or subtract 6.5 cm for a girl. The result is a midpoint, and most children land within about 8.5 cm (3.3 in) above or below it.
- What is the mid-parental method?
- The mid-parental method is a simple, widely used way to estimate a child's adult height from the parents' heights. You take the mid-parental height — the average of the mother's and father's heights — then add 6.5 cm for a boy or subtract 6.5 cm for a girl to account for the typical difference between adult male and female height.
- How accurate is the child height predictor?
- It is a rough estimate, not a guarantee. The method points to a likely midpoint, but real adult heights commonly fall within a range of about 8.5 cm (3.3 in) on either side. It does not account for nutrition, health conditions or growth patterns, so treat the number as a fun starting point rather than a precise forecast.
- Does nutrition and genetics affect height?
- Yes. Genetics set much of a child's height potential, which is why the parents' heights are useful, but nutrition, sleep, general health and environment all play a real part. Good nutrition during the growing years helps a child reach the upper part of their genetic range, while illness or poor diet can hold growth back. This estimate cannot capture those individual factors.
- When do kids stop growing?
- Most girls reach close to their adult height by around 14 to 15 years of age, and most boys by around 16 to 17, though the timing varies a lot from child to child. Growth slows and then stops once the growth plates in the long bones close after puberty. Some teens have later growth spurts than others.
- Should I ask a pediatrician about my child's height?
- Yes, if you have any concern. This tool is an informational estimate for curiosity and is not medical advice. Genetics and nutrition vary widely from child to child, so if you are worried about your child's growth, height or development, speak with a pediatrician who can track growth on proper charts and advise you.