How this calculation works
Average the two measured parental heights. The boy formula adds half of five inches to that average and the girl formula subtracts it. The displayed band uses the AAP’s illustrative margin of about four inches.
Mid-parental estimate = average of biological parents’ heights ± 2.5 inches (6.35 cm).A worked example
For parental heights of 165 and 180 cm, the average is 172.5 cm. The boy formula gives a midpoint of 178.85 cm.
Good to know
A rough educational estimate with a wide range. It excludes current growth pattern, puberty timing and bone age. Speak with a pediatrician about growth concerns.
Reference: American Academy of Pediatrics mid-parental method (opens in a new tab) ↗
How the inputs affect the result
Measure parental heights with shoes removed and use one unit consistently. The estimate is most informative as rough family-height context alongside growth history.
The adjustment has the opposite sign.
Where the calculation applies
A rough educational estimate with a wide range. It excludes current growth pattern, puberty timing and bone age. Speak with a pediatrician about growth concerns.
For a related calculation, see the Height converter for feet inches metres and centimetres.
Read more: American Academy of Pediatrics mid-parental method (opens in a new tab) ↗
A few questions, answered
Is the range a guaranteed outcome?
The band is a rough illustration of prediction uncertainty. Individual growth can fall outside it.
What does the “Girl formula with the same heights” setting illustrate?
The adjustment has the opposite sign.