A lot of parents wonder (and worry) about how tall their child will be. It is natural to consider what the future may hold for your child. You don’t have to be a father that dreams about his son playing professional sports or a mother raising a broadway dancer to be curious about what height your child will stop growing.

There are plenty of advantages to being both tall or short. Parent’s obsession with the height of their children is often more about looking at ourselves and considering what we have contributed to our child. What genes have we passed on? Will he grow up to be tall like his dad one day? Will she be sharing clothes with her mom one day soon? This makes sense as genetics play the largest role in the child’s final adult height.

Science actually does a decent job at helping us predict where children will fall on the growth chart, and so do some of the old wives tales. However, parents have to wait a few years before they can start to calculate how tall their kid will grow. Both the scientists and the old wives tales acknowledge that birth height is not a terribly accurate predictor of adult height. Still, parents are apt to believe that a baby born long will grow tall one day. The range for most newborns is between 18 and 22 inches.

Predict Your Child’s Adult Height

If you ask your grandmother to predict your child’s height she might tell you the 2 x 2 method, height at 2 multiplied by 2, will estimate how tall any kid will be as an adult. In that world, if you want your child to grow up to be six feet tall the first big hurdle is to be 3 feet tall by age two. Consider that the average height of a two year old is about 34 inches and a typical two year old is expected to grow about 2 inches per year until they reach puberty (and its accompanying growth spurt).

Another popular method used to estimate height is based on how tall the parents are. The mid-parental height method helps you estimate your child’s height before they are even born. All it requires is for parents to add together their respective heights and then divide by two to get the average and then add 5 inches for a boy or subtract 2 inches for a girl. Genetics continues to be the dominant determinant in how tall someone will be.

Growth in children can be negatively impacted by several factors. The most meaningful one is often nutrition as eating disorders or malnutrition can stunt growth spurts. Similarly childhood illnesses, obesity, and some medications can slow down the growth of a child and impact how tall they end up. This could add up as every extra inch in height is worth almost $1,000 in increased annual earnings according to some sociologists.

Scientists have found that the best time to predict a child’s height is actually 4 years of age. A age 4 the prediction is fairly accurate as the standard error is only 4-5 cm in both sexes. Boys are fairly more predictive at that age as about 80% of a boys final adult height can be explained by the height at age 4. For girls it is a bit lower with about 2/3 of a woman’s height being explained by her height at age 4.

Predicting a child’s height accurately can be helpful to parents along with doctors and other professionals. To make the prediction a parent or doctor can compare the child’s height at age 4 to the growth chart. If the child is in the 90% of height at age 4, he has about an 8 in 10 chance of being in the 90% of height when he reaches adulthood.

After age 4 and into adolescence the predictive power of the child’s height actually starts to diminish. This is due to the variability of kids entering and exiting puberty at different times. At age 14 the height of a boy is predicting only 66% of his final adult height. As boys start to shave they are usually about done growing. Girls usually grow about another 2 inches after they have their first menstrual period.

How Tall Will My Child Be?

Parents trying to predict the adult height of their son or daughter should remember these three simple methods for making an estimate:

• 2 x 2 Method: The two by two method is a simple estimate that has parents double the height of their two year old to predict their adult height.
• Mid-Parental Method: Predict the child’s final adult height by adding together his parent’s heights and dividing by 2. Then add 5 inches for a boy and subtract two inches for a girl.
• 4 Year Old Equation: Compare your child at age 4 to the growth chart and determine his percentile. Transfer that percentile to the adult height for the proper sex.

Parents interested in predicting the adult height of their children should first look at themselves. The genetic they contributed are the strongest determinant in a child’s final height. For those looking at their child lagging behind their classmates in height, or maybe those with a tall child, consider what age they are and if the height is a reflection of puberty or a good estimate of what lies ahead.