In the adult Rule of Nines, what percentage is attributed to the chest (front) surface?

• A. 18%
• B. 4.5%
• C. 1%
• D. 9%

Answer: (D)

The key idea is how the Rule of Nines estimates burn size. The chest front is part of the anterior trunk, which totals about 18% of body surface area in an adult. The chest front represents roughly half of that anterior trunk, so it accounts for about 9% of the total body surface area. That’s why the chest (front) surface is 9%.

In other words, 18% would cover the entire anterior trunk, while 1% is the perineum, and 4.5% isn’t a standard division in the Rule of Nines.