To measure a burn in an adult, you use the rule of nines. But first, what is a burn?

Burns damage the skin or tissues of the body. Burns can be caused by chemicals, electricity, fire, liquids that are hot, or even the sun.

Now there is a plant that have been recently discovered in Virginia (and other locations) that can cause blindness and third-degree burns. This is the giant hogweed plant. If you see a plant you are not familiar with, it’s important to not touch it.

Some burns are more severe than others. Burns can be classified by first-degree burn, second-degree burn, third-degree burn, or fourth degree burn.

First-degree burn:

  • Affects the epidermis (outer skin layer)
  • Burn site is red, painful, and dry
  • No long-term damage to the tissue

Second-degree burn:

  • Affects the epidermis
  • Part of the dermis layer is also affected
  • Burn site is red, blistered, swollen, and painful

Third-degree burn:

  • Affects the epidermis and dermis layer
  • Subcutaneous layer may be affected
  • Burn site is white or charred

Fourth-degree burns:

  • Damage to the bones, muscles, and tendons
  • Nerves are destroyed along with sensation to the area

NCLEX Burns Tips

  • Risk for hypovolemic shock with severe burns
  • Fluid replacement is needed with severe burns
  • Lactated Ringer’s is most commonly used IV fluid therapy, which is an isotonic solution.
  • Rule of nines is a formula used to calculate the percentage of the adult body that has been burned.

What is the rule of nines?

The rule of nines uses the total body surface area (TBSA) that has been burned to estimate the percentage of the adult body that has received the burn. Using the rule of nines help us determine how severe the burns are on the adult body.

Knowing how to use the rule of nines to calculate properly is critical for the nursing management to help decide how to treat burn victims.

How do you use the rule of nines to measure a burn?

Each body part is measured as 9% of the body.

Head – 9% of the total body surface area
Anterior torso – 18% of the total body surface area
Posterior torso – 18% of the total body surface area
Each arm – 9% of the total body surface area
Genitalia – 1% of the total body surface area
Each leg – 18% of the total body surface area

Rule of Nines Calculation NCLEX Tips:

  • Front of head is 4.5% and back of head is 4.5%. If only the front of the head has been burned, you do not calculate it as 9%. You only calculate 4.5%.
  • The entire torso is 36% of the body.
  • Both arms are 18% of the total body surface area. Each arm is 9%. If only the front of the arm is burned, then that is 4.5%. If only the back of the arm is burned, that is 4.5%.
  • Both legs is 36% of the total body surface area. If only the front of the leg is burned, then it is 9% of the total body surface area. If only the back of the leg is burned, it is 9% of the total body surface area. If the entire leg is burned, it is 18% of the total body surface area.

Use your new knowledge and measure a burn using the rule of nines now!

Rule of nines calculation: The front of the head and the right arm

  • Front of the head – 4.5%
  • Right arm – 9%

Total body surface area affected by burns = 13.5%

Rule of nines calculation: Torso, head, and both arms

  • Torso – 36%
  • Head – 9%
  • Both arms – 18%

Total body surface area affected by burns = 63%

Rule of nines calculation: Front right leg, genitalia, right arm

  • Front of the right leg – 9%
  • Genitalia – 1%
  • Right arm – 9%

Total body surface area affected by burns = 19%

Rule of nines calculation: Chest, front of the right arm, front of head, gentalia, and right leg

  • Chest – 18%
  • Front of the right arm – 4.5%
  • Front of the head – 4.5%
  • Gentalia – 1%
  • Right leg – 18%

Total body surface area affected by burns = 46%


HT: Emergency Medical Counsel