Rule of 9 in assessment of burns

The rule of nines is used to calculate the percentage of burns in assessment of a burn victim. Note that a patient’s palm is approximately 1% TBSA and can be used for estimating patchy areas.

  • Head/neck – 9% TBSA
  • Each arm – 9% TBSA
  • Anterior thorax – 18% TBSA
  • Posterior thorax – 18% TBSA
  • Each leg – 18% TBSA
  • Perineum – 1% TBSA




With pediatric patients, the head is a proportionally larger contributor to body surface area (BSA), while the upper legs contribute less. This difference is reflected in the slight differences noted in the pediatric Lund- Browder diagram. A useful tool for estimating BSA of spotty burns is the close approximation of just less than 1% BSA to the patient’s palm size. Only second-degree burns or greater should be included in the TBSA determination for burn fluid calculations.

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