How to Scientifically Predict Your Kid's Grown-Up Height

mom measuring daughter growth

It's something parents of every stature can't help but wonder: How tall will my baby grow to be? Unfortunately, there's no way to know for sure exactly how big your little one will get, but doctors do have some fairly accurate ways of predicting kids' eventual height. (And some ways, it turns out, are more accurate than others.)

The least accurate method of guessing whether your kid will be physically diminutive or domineering is basing your prediction on how many inches long your baby was at birth, says Joseph Gigante, M.D., professor of pediatrics at Vanderbilt University School of Medicine. 

"Parental heights are much better predictors of final adult height than the infant’s birth length," says Gigante. "It is not a coincidence that many short parents have short children and many tall parents have tall children."

But, Gigante adds, you can't assume your child's height will match yours perfectly. "Height is not solely based on genetics, as evidenced by identical twins sometimes having different heights," he says. "A variety of factors can affect growth, including nutrition, chronic diseases, endocrine diseases, genetic diseases, and psychosocial factors."

More from CafeMom: 9 DIY Growth Charts to Stylishly Track Your Kid's Height

So, allowing for those variations, which method of predicting future height is the best? Here are a few to try:

1. The Mid-Parental Method

Gigante calls this formula the most accurate. It's used by pediatric endocrinologists when patients are referred to them for problems with growth, and it goes like this:

Boy’s target height (in centimeters) = Father’s height (cm) + Mother’s height + 13 cm, divided by 2

Girl’s target height (in centimeters) = Father’s height (cm) + Mother’s height − 13 cm, divided by 2

(Get out your calculator and try it with your own parents and your height -- did it work?)

2. Two Years Times Two Method

According to Gigante, this method is less accurate than the previous, but it's quick and easy: Simply double your child's height at age 2.

3. X-Ray Method

After your child turns 2, your pediatrician can take an X-ray of her hand and wrist to determine skeletal or bone age; this, compared with other data, can help to predict her height as an adult. (Note that this method isn't used often, as doctors generally prefer to use radiation only when absolutely necessary.)

Happy guessing!