Height is determined 70% by genetics and 30% by environmental factors like nutrition, health, and exercise. There are many other variables, so the science of height prediction is not 100% accurate. However, there are two methods that can give you a good estimate as listed below. This app implements both the Mid-parent method and the more accurate Khamis-Roche method. Tracking your child's height with this app can show you if your child is developing normally.
This method can be used if your child is less than 4 years old. Derived from a 1948 article by Horace Gray in the journal of Child Development, it is still widely used today. The margin of error is +/- 4 inches or 10.16 cm. This is a simple formula where the adult the adult height is calculated from the parents' height and the child's gender.
This method can be used for children 4 to 17 years old. Developed by Dr. Khamis and Dr. Roche, this method is around 90% accurate. It uses the child's age, gender, height, weight, parents' height along with some scaling factors and equations to predict the child's adult height.
The Bone-Age method is more accurate than the Kkamis-Roche method, but it requires that an X-ray of the hand. Obviously, Adult Height Calculator cannot take X-rays! Maybe a future version of our smart phones can :)