Critical Care Trauma Centre


Thermal Burns                               

Determination of Burn Type

Management and Monitoring of the Burned Patient

How is the "Percentage of Burned Area" Calculated?
Estimation of the size of the burn is done using the "rule of nines" shown in Diagram 2.  The corresponding area of burn is identified on the diagram, and the total percentage is calculated as the sum of the burned areas. 

The type or thickness of the burn can also be recorded on the diagram.  Many burns are mixed in nature, for example, the outer edges may be partial thickness, while areas of deep partial and full thickness burns may extend toward the center.  The appearance of the burn, along with the presence of blanching, blisters and pain helps to determine the extent of the injury. 

The percentage of burns may change as the tissue injury evolves and more extensive tissue damage becomes evident.  Infection can increase the severity of the burn over the course of the injury.

Diagram 2

Derek Brzozowski and Brenda Morgan.  (October 23, 2000)


Thelan, L., Urden, L., Lough, M., & Stacy, K. Critical Care Nursing: Diagnosis and Management. Mosby: Toronto.  pp. 1141-1170.