Wallace Rule of Nines

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The Wallace Rule of Nines calculator computes the percent of a Body Surface Area that is burned based on the Wallace Rule of Nines. /attachments/b112e02b-658c-11e7-9770-bc764e2038f2/513_Degree_of_burns.jpg Burn Percentage

INSTRUCTIONS: Enter the following estimated percentages:

(H) % of the head burned.
(LA) % of the left arm burned.
(RA) % of the right arm burned.
(C) % of the chest burned.
(A) % of the abdomen burned.
(B) % of the back burned.
(G) % of the groin burned.
(LL) % of the left leg burned.
(RL) % of the right leg burned.

Percent BSA (%BSA): The calculator returns the percent of the burned Body Surface Area.

Burn Surface Area

The Wallace Rule of Nines can be used to approximate the percent of a patient that is burned. It applies a percent of Body Surface Area, often a multiple of 9, for different body parts as follows:

(9%) Entire head
(9%) Complete left arm
(9%) Complete right arm
(9%) Entire chest
(9%) Entire abdomen
(18%) Complete back
(1%) Groin
(18%) Complete left leg
(18%) Complete right leg

Example

If you compute the body surface area of a person using one of the standard body surface area methods (e.g. Takahira Body Surface Area) and get a BSA of 2 square meters, and then note that the patient’s skin issue (e.g. burn) is on half (50%) of his chest and all (100%) of an arm, you can use the Wallace Rule of Nine as follows:

Burn Area on Chest = 50% * 9% * 2 square meters = 0.09 square meters
Burn Area on Arm = 100% * 9% * 2 square meters = 0.18 square meters
Total Burn Area = 0.09 + 0.18 = 0.27 square meters of skin

This Wallace Rule of Nines Calculator makes the process simpler. In this example, you would enter 50% for the chest and 100% for the arm. The calculator would return 13.5%. That's the total estimate of the body surface area that is burned. You then multiply 13.5% times 2 square meters to get 0.27 square meters of burned skin.

Body Surface Area (BSA) is the measured or calculated surface area of a human body frequently used in physiology and medicine. For many clinical purposes BSA is a better indicator of metabolic mass than body weight because it is less affected by abnormal adipose mass. Estimation of BSA is simpler than many measures of volume.

BSA Calculators vs Inputs
Method	Height	Weight	Gender
Mosteller	x	x
Gehan and George	x	x
Boyd	x	x
DuBois	x	x
Haycock	x	x
Fujimoto	x	x
Takahira	x	x
Schlick	x	x	x
Costeff		x
Wang Hihara	x	x

Demographic BSA Means

**Mean Body Surface Area (male and female)**
Age Range	Male	Female
Neonate	0.243 m²	0.234 m²
2 years old	0.563 m²	0.54 m²
5 years old	0.787 m²	0.771 m²
10 years old	1.236 m²	1.245 m²
13 years old	1.603 m²	1.55 m²
18 years old	1.98 m²	1.726 m²
20 to 79 years old	2.06 m²	1.83 m²
80 and above	1.92 m²	1.638 m²

Body Surface Area (BSA) Calculators

Other BSA Applications

The BSA Compare function lets you enter a body surface area and choose a demographic (above) to compute the percent compared to the mean.
Wallace Rule of Nines: This computes a percentage of the human body for burn victims based on percentages allocated to different body parts.
Rule of Fives: This computes a percentage of the human body for obese burn victims.
Parkland Replacement Fluid: This compute the volume of replacement fluids needed in the first 24 hours based on the patients weight (mass) and the percent of their body that has been burned.
BSA Percent: This computes a body surface area based on the total body surface area and a percent..

References:

Image of Human Body from OpenStax College. Used through CC 3.0. Source Anatomy & Physiology, Connexions Web site. http://cnx.org/content/col11496/1.6/, Jun 19, 2013.