dad checking his daughter's height against the wall
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Here's How To Approximate How Tall Your Kid Is Going To Be

It’s not an exact science.

So much of your child’s future is a mystery, and that’s one of the fun (and sometimes scary) parts of parenting. In addition to daydreaming about what your child’s future hobbies and interests will be, you may also think about what they’ll look like. The good news is that you’re in the right place if you’ve ever found yourself wondering, how tall is my kid going to be?

Or maybe your child is starting to take an interest in height (and thinks that the taller a person is, the older they are). If your child has started to ask you, “how tall am I going to be?” read on to find out how to give them the best possible answer, according to a pediatrician. But spoiler alert: the most accurate response may be a shoulder shrug.

Is there a way to tell how tall your kid will be?

The short answer here is that there’s no real way to definitively predict how tall a child will be.“I don’t actually believe that [a child’s final height] is possible to predict,” Dr. Jessica Madden, a board-certified pediatrician, neonatologist, and medical director of Aeroflow Breastpumps tells Romper. She adds that when she was in her pediatric residency training, she was taught to use a formula that takes the mother’s height and father’s height into account to predict a baby’s future adult height. “Based on this method, which is called the mid-parental height method, you add both parents' heights together and divide by two to obtain a ‘mid-parental’ height. If your child is a boy you are supposed to add 2.5 inches to the mid-parental height to predict future adult height, and for girls you are supposed to subtract 2.5 inches from the mid-parental height to predict future adult height,” she says.

She stopped using the mid-parental method after a while since it seemed “so inaccurate” in most of her adult friends and peers situations. “Now when my patients’ parents ask me about future height prediction I tell them the truth — that I don’t have any idea!’’ You probably know siblings of extremely different heights (for example, my sister is just over five foot and I’m about 5’6” and we have the same parents) and this method would suggest that siblings of the same sex are the exact same height.

The mid-parental method is supported by the the American Academy of Pediatrics' though they do note on their website that “you can expect a margin of error of about four inches up or down.”

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What is the Khamis Roche method?

You may have heard of the Khamis Roche method, which takes a number of variables into consideration including parents’ heights, child’s height and weight and current age. “I have not personally used this method but there are multiple height prediction calculators that you can find online that use this method,” Dr. Madden says. These methods tend to be Eurocentric, leaving out a large swath of the population. “Many of the current height predictor formulas, such as the Khamis Roche method, are based on white children from the U.S. and/or Europe. These methods are outdated and do not reflect the diverse and heterogeneous background of American children in the present day,” Dr. Madden says.

Can I double my kid’s height at age 2 to estimate their full grown height?

Some say you can double your child’s height at age 2 to get their final height, but Dr. Madden is skeptical of this method as well. “I don’t think there is any truth to this one,” she says. “I just did the calculations myself and it looks like this method overestimates children’s future adult height by quite a bit. The average 2 year old boy in the U.S. is 34.2 inches — double this is a prediction of 78.4 inches [or] 6’6. The average 2 year old girl in the U.S. is 33.5 inches , so double this is a prediction of 67 inches, 5’7.” She adds that when you consider the average adult male in the U.S. is 5’9 and the average adult female in the U.S. is 5’4, this doesn’t really hold up.

Other factors that influence a child’s height

It’s estimated that as much as 80% of a child’s final height is genetic, meaning it’s largely determined before they’re even born. Factors that make up the additional 20% of the puzzle include things like nutrition, whether or not a mother smokes, and even birth order. It’s widely known that people who smoke during their pregnancy often give birth to smaller, underweight babies, but this also extends into childhood; one 2014 study out of Brazil found that children of smokers are shorter through adolescence (and interestingly, a second study showed that kids who smoke from ages 12-17 may also end up shorter than nonsmoking peers).

Plus it turns out there actually is something to the idea of drinking milk to grow strong and tall. As reported in Scientific American, “The most important nutrient for final height is protein in childhood. Minerals, in particular calcium, and vitamins A and D also influence height. Because of this, malnutrition in childhood is detrimental to height.” A British study in The Guardian also indicated that younger siblings (especially those with brothers) grow more slowly, though this likely has more to do with food scarcity than it does actual birth order— the thought is that in some situations where multiple children are present there may be food insecurity that mostly affects a youngest child.

Should I be concerned about my child’s height?

Your pediatrician should alert you if anything seems off with your child’s growth and it’s important to remember that kids grow at varying speeds. If it sounds helpful (and won’t just make you more anxious) you can check out the CDC’s growth charts to see what curve your kid is on (like every other method, these are also estimates). Generally if your child’s growth rate seems slow or has stopped and they’re in the fifth or lower percentile your doctor will want to look into potential causes.

Remember, you can speculate but there’s no absolute way to predict how tall your child will be. As Dr. Madden says, “it’s really difficult to obtain an accurate prediction of how tall your child will be unless both parents are very short or very tall — in which case a child will likely also be very short or tall due to such a strong genetic predisposition for height.”