The rule of nines is a standardized method used to quickly assess how much body surface area (BSA) has been burned on a patient. This rule is only applied to partial thickness (2^nd degree) and full thickness (3^rd degree) burns. The diagram below depicts BSA percentages for adults and infants of one year or less. For children over the age of one year, please see the formula below.

For children over the age of one year, for each year above one, add 0.5% to each leg and subtract 1% for the head. This formula should be used until the adult rule of nines values are reached. For example, a 5-year old child would be +2% for each leg and -4% for the head.

An alternative method to calculating the BSA is to compare it to the size of the patient’s palm, which equates to approximately 1% BSA. For example, if a burn area is the size of (5) palm surfaces, the burn would be roughly 5% BSA. This method can be used to estimate the BSA for both adults and pediatrics. In most cases, you may find it more useful to use the rule of nines when evaluating larger burn areas and the “palm” method for smaller burn injuries.

Burns are classified as superficial (1^st degree), partial thickness (2^nd degree) or full thickness (3^rd degree) depending on the depth of the injury. For the most part, burns can be quickly classified during the initial assessment or primary survey and a more detailed evaluation can be conducted during the focused history and physical examination.

Superficial (1^st Degree)

Epidermis

• The skin will appear red without any blisters.
• The area will be painful and tender.

Partial Thickness (2^nd Degree)

Epidermis, Dermis

• The skin will appear red or white with blisters.
• The area will be severely painful.

Full Thickness (3^rd Degree)

Epidermis, Dermis, Subcutaneous Fat, Muscles

• The skin will appear leathery and dark brown to black.
• The inner area will not be painful, but the outer edges will be.