Parents often wonder how tall their child will be as an adult.
About this calculator
Parents often wonder how tall their child will be as an adult. Genetics explain most of the answer. The mid-parental height formula is the standard tool paediatricians use for a quick estimate before puberty.
For boys, add both parents' heights in cm, add 13, and divide by two. For girls, subtract 13 instead of adding. The 13 cm gap reflects the average height difference between men and women in the same family. Example: father 175 cm, mother 162 cm gives a boy prediction of (175 + 162 + 13) ÷ 2 = 175 cm and a girl prediction of (175 + 162 − 13) ÷ 2 = 162 cm.
Real outcomes scatter around this number. About two-thirds of adults land within ±8.5 cm of the prediction. Nutrition, chronic illness, sleep, and timing of puberty can push a child above or below the range. This tool does not replace growth charts or a doctor's assessment.
Use the [[bmi]] calculator to track weight-for-height in children and teens. The [[ideal-weight]] calculator shows healthy weight ranges at a given height. For adults converting units, pair this with any length converter on the site.
Common uses
- Estimating adult height for a 10-year-old before a paediatric check-up
- Comparing boy vs girl predictions in the same family
- Understanding whether a child
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Frequently asked questions
How accurate is the mid-parental height formula?
It predicts within ±8.5 cm for about two-thirds of adults. That is useful for setting expectations but not exact. Growth hormone issues, malnutrition, or early/late puberty can shift the final height outside the range.
Why do boys add 13 cm and girls subtract 13?
The 13 cm adjustment accounts for the average sex difference in height within families. Without it, boys and girls would get the same prediction from the same parents, which does not match real data.
My child is shorter than predicted — should I worry?
Track height on a growth chart at regular paediatric visits. A child below the predicted range but growing steadily along their own curve is often fine. Sudden slowing, pain, or falling off the chart warrants a doctor visit.
Does child age change the prediction?
No. The formula uses parental heights only. Age is shown for context. Before puberty, current height tells you little about adult height unless plotted on a standard growth chart.
Can nutrition make a child taller than predicted?
Severe undernutrition can stunt growth below genetic potential. Good nutrition lets a child reach their genetic ceiling but rarely pushes far above the mid-parental range. Sleep and overall health matter during growth spurts.