The Rule of Nines also is used in first aid to calculate the extent of burns.

Most parts of a human body consists of nine percent of the outer surface area.

  • Head: 9% (4.5% front, 4.5% back)
  • Chest to the lower rib cage: 9%
  • Abdomen, from rib cage to groin area: 9%
  • Back, from neck to bottom of rib cage: 9%
  • Lower back, from bottom of rib cage to below buttocks: 9%
  • Front of left leg: 9%
  • Front of right leg: 9%
  • Back of left leg: 9%
  • Back of right leg: 9%
  • Left arm: 9% (front: 4.5%, back: 4.5%)
  • Right arm: 9% (front: 4.5%, back: 4.5%)
  • Groin: 1%

When assessing the victim, count up each area with a burn. Figure out the percentage, then you can go to HOWTO: Treat thermal burns in the backcountry to figure out what to do.