Child Height Predictor
Predict a child's adult height from the parents' heights using the mid-parental method, with the expected range and how genetics really works.
كيفية استخدام هذه الحاسبة
- 1Choose the child's sex — the adjustment differs by about 5 inches.
- 2Enter both biological parents' adult heights as accurately as you can.
- 3Read the predicted height, then pay attention to the range rather than the single number.
طريقة الحساب
Mid-parental (Tanner) height prediction
mid-parental = (mother's height + father's height) ÷ 2 boy: predicted = mid-parental + 6.5 cm (+2.6 in) girl: predicted = mid-parental − 6.5 cm (−2.6 in) expected range = predicted ± 10 cm (±4 in)
Averaging the parents captures the shared genetic contribution. The ±6.5 cm adjustment is half the average adult height difference between men and women, which is about 13 cm — it converts the sex-neutral parental average into a prediction for a specific child. The ±10 cm range is not a formality: it reflects that height is influenced by hundreds of genes plus environment, so siblings with identical parents routinely differ by several inches.
مثال محلول
A boy whose mother is 5'5" (165 cm) and father is 5'10" (178 cm): the mid-parental height is 171.5 cm, plus 6.5 cm for a boy gives 178 cm — about 5'10", with an expected range of roughly 5'6" to 6'2".
Child Height Predictor: الدليل الكامل
How much of height is genetic
Twin and family studies put the heritability of adult height at roughly 80% in well-nourished populations. That does not mean 80% of any individual's height comes from genes — it means about 80% of the *variation between people* in that population is attributable to genetic differences.
Height is highly polygenic: over 700 genetic variants have been associated with it, each contributing a fraction of an inch. This is why children regularly fall outside their mid-parental prediction, and why two tall parents can have an average-height child through ordinary genetic recombination.
The remaining variation is environmental, and nutrition dominates it. Average height in South Korea rose by about 6 inches over the twentieth century, and in the Netherlands by around 8 — far too fast for genetics, and almost entirely down to childhood nutrition and disease burden.
Growth patterns and when they matter
Growth is fastest in infancy — around 10 inches in the first year — then settles to roughly 2 to 2.5 inches a year through childhood. The pubertal growth spurt adds most of the remainder, typically between 10 and 14 for girls and 12 and 16 for boys.
Girls generally finish growing around 14 to 16, boys around 16 to 18, when the growth plates fuse under the influence of oestrogen. After fusion, no intervention increases height.
Timing creates most of the anxiety. A late-developing boy can be the shortest in his class at 14 and among the tallest at 18. Paediatricians distinguish this constitutional delay — which needs no treatment — from genuine growth failure by tracking the child's percentile curve over time rather than any single measurement.
Better predictors than the parental average
A bone age X-ray of the hand and wrist shows how much growth plate remains, and combined with current height gives a considerably more accurate prediction than the mid-parental method. It is the standard tool when there is a clinical question.
There is also a widely used rule of thumb: a child's height at age two is roughly half their adult height. It is less accurate than bone age but needs no equipment.
Crossing percentile lines is the signal clinicians watch for. A child who has tracked the 50th percentile and drops toward the 10th warrants investigation — growth hormone deficiency, thyroid problems, coeliac disease, and Turner syndrome are all treatable and all present this way.
What actually supports reaching genetic potential
Adequate protein, calcium, vitamin D, and total calories through childhood and adolescence. Chronic undernutrition is the single largest suppressor of adult height worldwide.
Sleep matters because growth hormone is released in pulses during deep sleep — school-age children need 9 to 11 hours, teenagers 8 to 10. Regular physical activity supports bone development, and no ordinary sport stunts growth, contrary to a persistent myth about weight training.
Nothing increases height beyond genetic potential in a healthy, well-nourished child. Supplements and devices marketed for height gain do not work, and growth hormone therapy is only appropriate for diagnosed deficiency under specialist care.
الأسئلة الشائعة
How accurate is the mid-parental height method?
It puts about two thirds of children within its ±4 inch range, which makes it a reasonable first estimate but a poor precise prediction. A bone age X-ray combined with current height is substantially more accurate when there is a clinical reason to know.
At what age do children stop growing?
Girls typically finish around 14 to 16 and boys around 16 to 18, when the growth plates fuse. Some boys continue slowly into their early twenties. Once the plates close, height is fixed.
Can a child be taller than both parents?
Yes, and it is common. Height is influenced by hundreds of genes, so a child can inherit a taller-than-average combination from both sides. Better nutrition than the parents had as children also contributes, which is why generational height gains have been so consistent.
Does anything actually increase a child's height?
Only removing the things holding it back. Adequate nutrition, sufficient sleep, treating chronic illness, and physical activity all help a child reach their genetic potential. Nothing exceeds that potential, and no supplement, stretching routine, or device changes adult height in a healthy child.