Enter the total area of the body part affected by burns into the calculator to determine the Rule of Nines.

Rule Of Nines Formula

The following formula is used to calculate the Rule of Nines.

RoN = (A * 9) / 100

Variables:

  • RoN is the result of the Rule of Nines
  • A is the total area of the body part affected by burns

To calculate the Rule of Nines, multiply the total area of the body part affected by burns by 9. Then, divide the result by 100. This will give you the percentage of the body that is burned according to the Rule of Nines.

What is a Rule Of Nines?

The Rule of Nines is a method used in emergency medicine to quickly estimate the total percentage of burn area in adults. The body is divided into sections of 9% or multiples of 9% (head and neck 9%, each arm 9%, each leg 18%, front torso 18%, back torso 18%, and genital area 1%). This helps medical professionals assess the severity of the burn and determine the necessary treatment.

How to Calculate Rule Of Nines?

The following steps outline how to calculate the Rule of Nines.


  1. First, determine the total area of the body part affected by burns (A).
  2. Next, multiply the total area by 9.
  3. Finally, divide the result by 100 to calculate the Rule of Nines (RoN).

Example Problem:

Use the following variables as an example problem to test your knowledge.

Total area of the body part affected by burns (A) = 18%