Teenagers can predict their final heights by looking at their parents' heights and by studying their own growth charts and completing a simple equation, according to WebMD. The formula may only predict a teenager's final height, and the predictions may not be accurate.
Teenage boys and girls can use one of two equations to determine their future height plus or minus two inches, according to WebMD. A girl can subtract 5 inches from her father's height then add her mother's height. Next, the product is divided by two in order to get the final predicted height in inches. A boy can add his mother's height plus 5 inches to his father's height, then divide the result by two in order to receive his final predicted height.
Final height can be affected by chronic illnesses, nutrition and early or delay growth among family members, WebMD states.