The entire trunk (front and back) of the body is what percent of body surface

Using the rules of nines with an adult, the percentage of the total body surface area of the anterior trunk or posterior trunk is 18%.  Rule of nines is a formula for estimating percentage of body surface areas, particularly helpful in judging the portion of skin that has been burned. For the adult, the head represents 9%; each upper extremity 9%; the back of the trunk 18%, and the front 18%; each lower extremity 18%; and the perineum the remaining 1%.