How to Calculate Adult Height

Written by alex brown
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How to Calculate Adult Height
There are several ways to predict your child's adult height. (family image by Mat Hayward from

Many parents are excited to speculate on what their young child will be when they reach maturity. Will they be going to the NBA? Should you contact USC to secure a football scholarship for your son? Or start teaching your daughter to dribble a basketball to practice early for her run on the University of Connecticut women's basketball team? There is no perfectly accurate way to calculate a child's adult height. However there are a number of methods, new and old, that can offer ballpark predictions.

Skill level:

Things you need

  • Internet
  • Tape measure

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  1. 1

    Double your child's height at age two. This is one of the oldest methods known and has garnered some relative validity. Have your child line up against a door frame. Use a pencil to mark where the top of their head reaches and use measuring tape to determine their current height. Multiply their current height by two and you have their adult height. For example, if your son is thirty six inches at age two, he would presumably grow to be 72 inches or 6 feet tall as an adult.

  2. 2

    Add the mother's height to the father's height and divide by two. Add three inches if it is a boy and subtract three inches if it is a girl. For example, if the mother is 62 inches and the father is 66 inches, you would do (62 + 66)/2 to equal 64. So a 67 inch (5' 7'') tall son or 61 inch tall daughter (5' 1'') This method is newer and moderately accurate. It has a plus or minus margin of error of about five inches.

  3. 3

    Calculate using the "Khamis-Roche Method." This method was created and published by Drs. Harry Khamis and Alex Roche in 1994. It uses a formula that inputs factors including your child's gender, the heights of both parents, the child's height, child's weight and child's age. Accuracy comes within 1.5 inches in healthy children. You can find many "Khamis-Roche" calculators online.

Tips and warnings

  • There are many height predicting calculators on the Internet, so experiment with many of them. Genetics and your child's gender are the most important factors in determining how tall your child will grow. Growth is also affected by nutrition and health problems.
  • Take your child to a doctor if you believe they are not growing at a healthy rate.

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