About Burns: Making the Diagnosis
A diagnosis is usually formed based on burn depth. However, a diagnosis might also be influenced by the extent of damage to the body. The extent of a burn is usually based on the "rule of nines": each arm is considered 9% of the body surface area, each leg is 18%, the back and front of the torso are each considered to be 18%, and the genital region is 1% of the surface area. Using these classifications, a physician can make a clear diagnosis.