In the Rule of Nines for an adult, each leg accounts for what percentage of body surface area?

• A. 4.5%
• B. 18%
• C. 36%
• D. 9%

Answer: (D)

In the Rule of Nines, body regions are assigned approximate percentages to quickly estimate burn size. For the legs, the entire leg accounts for 18% of total body surface area, because the front of the leg is about 9% and the back of the leg is about 9%. So if the question asks how much each leg contributes, the answer is 18%, not 9%. The 9% figure would reflect only one surface of a leg (either the anterior or posterior), not the whole leg. For reference, other regions are head and neck 9%, each arm 9%, anterior trunk 18%, posterior trunk 18%, and the perineum 1%.