How to Predict Your Child’s Adult Height
The formula pediatricians use to estimate children’s future height — with a worked example and the limits you need to know.
Educational content, not medical advice. Height estimates do not replace a pediatrician’s assessment. If you have concerns about your child’s growth, consult a doctor.
The most widely used way for pediatricians to estimate a child’s adult height is the mid-parental height formula: for boys, (father’s height + mother’s height + 13) ÷ 2; for girls, (father’s height + mother’s height − 13) ÷ 2. The result has a margin of about ±8.5 cm.
This estimate works because genetics accounts for about 80% of final height. But it is a statistical starting point — not a prophecy. Nutrition, health, and the individual pace of puberty move the final result within that margin.
Below: the formula with an example, when it works best, and when to doubt the number.
The formula, with an example
Add the parents’ heights in centimeters, adjust for the child’s sex, and divide by 2:
- • Boys: (father + mother + 13) ÷ 2
- • Girls: (father + mother − 13) ÷ 2
Calculate in seconds
Doing the math by hand is simple, but our calculator applies the formula automatically and shows the full estimate range:
Limits you need to know
The formula assumes average conditions. It loses accuracy when:
- • There is a large height difference between the parents (the real margin grows)
- • The child experienced malnutrition, chronic illness, or very early/late puberty
- • The parents are not the biological parents (the genetics considered are biological)
- • The child is still a baby — the prediction gets more reliable from ages 2–3 onward
What to do with the number
Use the prediction as a calm reference — for example, to buy clothes ahead of time or satisfy curiosity. Don’t use it to set rigid expectations for the child.
The real warning sign is not the prediction itself, but the growth curve: if the child has been dropping in percentile consistently, that does deserve a conversation with the pediatrician.
Frequently asked questions
Is the prediction reliable?
It is the best simple estimate available and is used by pediatricians worldwide — but with a ±8.5 cm margin. For an accurate assessment, the pediatrician combines the formula with the growth curve and bone age.
Do exercises or supplements change the predicted height?
There is no evidence that exercises, stretching, or supplements increase height beyond genetic potential. Good nutrition and adequate sleep in childhood ensure the child reaches that potential — not exceeds it.
At what age does the prediction get more accurate?
From ages 2–3 onward, the child’s growth curve already gives solid clues. During puberty, the prediction combined with bone age is the most accurate.