Adult Height Predictor
Estimate how tall a child may grow, based on the parents’ heights.
Mid-parental method: boys = (father + mother + 13 cm) / 2, girls = (father + mother − 13 cm) / 2. Most children end up within about 8.5 cm of this figure. An estimate, not a medical assessment.
How the adult height predictor works
This calculator uses the mid-parental height method, the same quick estimate many pediatricians reach for at a first check-up. It adds the mother’s and father’s heights, adjusts for the average 13 cm gap between adult men and women, and divides by two. For a boy you add 13 cm before dividing; for a girl you subtract 13 cm.
Say the mother is 165 cm and the father is 178 cm. A son’s predicted height is (165 + 178 + 13) / 2 = 178 cm, about 5’10”. A daughter’s is (165 + 178 − 13) / 2 = 165 cm, about 5’5″.
How accurate is it?
Height is strongly inherited, but it isn’t fixed by the parents alone. Most children land within roughly 8.5 cm (about 3.5 inches) of their mid-parental figure, which is why the tool shows a range rather than a single promise. Siblings with the same parents can easily end up 10 cm apart.
Things that push the result up or down
- Nutrition, especially protein, calcium and vitamin D during childhood
- Sleep, since growth hormone is released mostly at night
- Timing of puberty: early bloomers often stop growing earlier
- Long-term illness or medication
- Genes from grandparents that the parents’ own heights don’t show
Celebrity examples
Famous families show how wide the spread can be. Some children of tall actors and athletes end up even taller than both parents, while others stay close to the shorter one. That’s exactly what the range in the result is for: it shows the likely window, not a fixed outcome.
When to talk to a doctor
If a child is growing much slower than their classmates, falls off their usual growth curve, or is far outside the predicted range, a pediatrician can check bone age and growth patterns. This tool is a fun estimate and a conversation starter, not a diagnosis.
Curious how an adult height compares worldwide? Try our height by country tool next.