How the prediction works
The mid-parental method takes the average of the two parents' heights and then adjusts for the child's sex, adding a few centimetres for boys and subtracting them for girls. The result is a single best-guess adult height.
Children inherit a large share of their height potential from their parents, which is why this simple average tends to land surprisingly close for most kids.
Reading the range
The tool also reports a likely range of roughly plus or minus 8.5 cm around the prediction. The bar chart shows the low end, the central prediction and the high end together, so you can see the spread rather than fixating on one number.
Most children finish growing somewhere inside that band. Landing toward the top or bottom is perfectly normal and influenced by factors beyond parental height.
What else affects adult height
Genetics set the broad potential, but several factors shape the final figure:
- Nutrition during childhood and the growth-spurt years.
- General health and any chronic illness.
- Timing of puberty, which varies widely between children.
- Sleep and physical activity over the growing years.
Note
This is an estimate based only on parental height and cannot account for an individual child. If you have concerns about a child growing much faster or slower than expected, a pediatrician can assess growth properly using growth charts and other measurements.
Formula
boy = (mother + father + 13) / 2; girl = (mother + father − 13) / 2 (cm)Frequently asked questions
- How accurate is this?
- Most children reach within roughly ±8.5 cm of the predicted height, but it is only an estimate based on parental height.