How to Estimate the Future Height of Kids
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There are several methods that can be used to find out how tall a child will be in the future. The calculator above uses the Khamis-Roche method for kids aged 4+ and the mid-parental method for newborns and younger children. The former method is actually considered pretty accurate to predict a kid’s height at adulthood.
Next, we’ll go through all the available techniques which you can utilize for the height calculation.
1- Khamis-Roche Method
The child’s adult height can be accurately calculated through an equation without needing to determine the skeletal age (i.e. take an x-ray). The formula to use includes the child’s stature, weight and mid-parent stature in addition to some constants that are based on the kid’s age and gender. The mid-parent stature is simply the average of the father’s and mother’s statures. This technique of height estimation is known as the Khamis-Roche method.
The Khamis-Roche method was developed by Wright State University in 1994 in Dayton, Ohio by Dr. Harry Khamis and Dr. Alex Roche. They published a paper that describes the method in details including the equation coefficients (1).
The downside of this method is it can be used for only children aged 4 years and older. You should utilize another method when trying to find the height of younger kids including infants and toddlers. Also, please note that the Khamis-Roche formula was developed based on Caucasian children, so it may not be accurate for other races.
2- Mid-Parental Method
We can utilize the genetic potential to predict a kid’s adult height, by averaging the heights of their parents. Boys tend to grow a bit taller so we add a few more inches and the opposite is true for girls. This technique is called the mid-parental method and it goes like this (2);
- Add the mother’s height to the father’s height in either inches or centimeters.
- Add 5 inches (13 centimeters) for boys or subtract 5 inches (13 centimeters) for girls.
- Divide by 2.
This simple formula is suited for younger kids (i.e. under 4 years) since it doesn’t take the child’s current weight/height into account.
3- Doubling Method
The formula for this method is quite simple, you find the child’s height at age of two then double it (2). The idea behind this formula is from two years old, most healthy children grow steadily at about 2 inches per year until they reach puberty (3). For girls though, it’s more accurate to use the height at age of 18 months instead since they grow more quickly than boys.
The doubling method is reliable but requires knowing the kid’s height at a specific young age (i.e. 2 years old) which may not always be possible.
4- Growth Charts Method
This height calculation method relies on the standard growth charts developed in many countries. For the US, the ones to use were created by the World Health Organization (WHO) and Centers for Disease Control and Prevention (CDC) (4)(5). You should use the WHO charts for children from birth up to 2 years and the CDC charts for those aged 2-17.
What you do is plot the child’s current height on the growth curves, follow along the percentile line and see where they end up as an adult. More detailed instructions on using the growth charts are provided by the CDC (6).
The growth charts do give accurate prediction of a child’s future height. But they probably require a bit more effort as compared to the other methods that involve a mere math equation (all excluding the bone age method). By the way, these charts are typically used to track the child development by height, weight and head circumference.
5- Bone Age Method
We saved this method for last because it requires a visit to the doctor (i.e. can’t be done from home)
The most accurate way of height prediction comes from using a child’s bone age. Basically, an x-ray is taken of the kid’s hand at the hospital. Then, the bones on the X-ray image are compared with X-rays images in a standard atlas of bone development, which is based on data from large numbers of other kids of the same gender and age (7).
If you don’t mind the trip to the hospital with your child and the radiation involved, this is a height calculation method you probably should consider since it has the top accuracy overall.
There you have it, several methods you could use for predicting how tall a kid will be at adulthood.
Remember though that all these calculation methods provide a mere estimate and not exact numbers. Because there are several factors that can influence a child’s height growth including genetics, physical activity, nutrition, medical conditions and sleep habits.
If you want the easiest method, just use the calculator provided on this page to avoid all the headache. Remember to select the preferred unit system (lb,ft or kg,cm) beforehand.
- Khamis H.J. & Roche A.F. (1994). Predicting adult stature without using skeletal age: the Khamis-Roche method. Pediatrics, 4(1), 504-7.
- Hoecker, J. (2022). What’s the best way to predict a child’s adult height? Mayo Clinic. https://www.mayoclinic.org/healthy-lifestyle/childrens-health/expert-answers/child-growth/faq-20057990/
- Bishop, S. (2010). Child’s height at age 2 may predict adult height. Mayo Clinic. https://newsnetwork.mayoclinic.org/discussion/childs-height-at-age-2-may-predict-adult-height/
- Centers for Disease Control and Prevention (2006). WHO growth charts. https://www.cdc.gov/growthcharts/who_charts.htm/
- Centers for Disease Control and Prevention (2000). Clinical growth charts. https://www.cdc.gov/growthcharts/clinical_charts.htm/
- Centers for Disease Control and Prevention (2010). Use and interpretation of the WHO and CDC growth charts for children from birth to 20 years in the United States. https://www.cdc.gov/nccdphp/dnpa/growthcharts/resources/growthchart.pdf/
- Durani, Y. (2021). X-ray exam: bone age study. Kids Health. https://kidshealth.org/en/parents/xray-bone-age.html/