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 (2nd degree) and full thickness (3rd 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.