How Tall Will Your Baby Be When He Grows Up? Calculating Height Early


Will your baby grow up to be tall or short? Image by roxinasz

Will your baby grow up to be tall or short? Image by roxinasz

Can you predict your future child’s height while you’re still pregnant? There are a number of ways to figure it out once your child is born, which often involve measuring your child’s height, weight and age. Let’s ignore these methods, like “double the height at age two” (which is less reliable for girls than boys), since you are still pregnant – instead, statistics may have the answer.

Simple Statistics To Predict Baby’s Future Height

The simplest statistics-based process to predict your fetus’s adult height is the Khamis-Roche Method. It does ask for the child’s current height and age, but you can calculate based on a reduced number of factors, so let’s skip to what you know during pregnancy: the height of each parent.

Some web sites offer online calculators for this. However, the Khamis-Roche Method is based on data from American Caucasians so the authors do not vouch for its accuracy for other racial groups or those in other countries.

The “midparent stature” is the average of the father’s and mother’s height. To get this number, add Mom’s height to Dad’s height, and divide the number by 2. Based on small samples of a few hundred students in first-year Anthropology classes, Prof. Hawks determined the statistically best equations in centimetres:

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  • A boy baby’s adult height will be about 72% of the midpoint height, plus 51 centimetres, or about 20 inches.
  • A girl baby’s adult height will be about 60% of the midpoint height plus 61 centimetres, or about 24 inches. (The calculation for girls is less accurate than the calculation for boys.)

So, if the mom is 5 feet tall, and the dad is 6 feet tall, the mid-point is Mom’s 5 feet plus Dad’s 6 feet divided by 2.

5+6=11 feet

11 / 2 = 5.5 feet

The prospective boy baby of this union would be 72% of 5 1/2 feet (3.96 feet) plus 20 inches (1.66 feet) or approximately 5 feet and 7 inches tall.

The prospective girl baby of this union would be approximately 60% of 5 1/2 feet (3.3 feet) plus 24 inches (2 feet) or approximately 5 feet and 3 inches tall.

Hawks also estimates that only about 72% of the child’s height is due to inherited genetic tendencies, and the rest is due to environmental issues. For example, poor nutrition may stunt the child’s growth.

Making Baby Predictions

It’s easy to find a baby gender predictor, do the math to figure out what eye color your baby may have, or even find a web site to predict the adult height of your infant, but in reality – you’re just going to have to wait and see. Have fun with all these predictors, but Decoded Pregnancy is not taking wagers!


Hawks, John. Heritability and Stature. (2011).  Accessed April 11, 2013. 
Khamis, Professor Harry. Stature Prediction. (2001). Wright State University.  Accessed April 11, 2013. 
O’Neil, Dennis. Mendel’s Genetics and Glossary of Terms. (1997-2012). Palomar College. Accessed April 11, 2013. 

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  1. […] The third and final article in my Decoded Pregnanacy series of “mathematical baby predictors while pregnant” is “How Tall Will Your Baby Be When He Grows Up? Calculating Height Early“. […]

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