Enter the total body surface area (TBSA)—the area of the entire body—and the burned area (BA) in the same units (commonly m²) to calculate the burn percentage (%TBSA burned).

Burn Percentage (%TBSA) Calculator

Best use: enter TBSA (total body surface area) and Burned Area to calculate Burn Percentage. (Optional: you may enter Burn Percentage to solve for Burned Area or TBSA.)

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Safety notice: This calculator is for educational use only and does not diagnose burn severity or replace medical evaluation. Seek urgent/emergency care for trouble breathing, suspected inhalation injury, electrical/chemical burns, deep/white/charred burns, burns to the face/hands/feet/genitals/major joints, large or worsening burns, severe pain, fever, or signs of infection (especially in infants or older adults). For professional guidance, consult resources such as the American Burn Association burn-center referral criteria.

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Burn Percentage Formula

The following formula is used to calculate the burn percentage (%TBSA burned) for a given total body surface area and burned area.

BP = (BA / TBSA) * 100

Variables:

  • BP is the burn percentage (%TBSA burned)
  • BA is the burned area (an area value in the same units as TBSA)
  • TBSA is the total body surface area (area of the entire body, often expressed in m²)

To calculate the burn percentage, divide the burned area by the total body surface area and multiply the result by 100 to get the percent of body surface burned.

What is Burn Percentage?

Burn percentage (often written as %TBSA burned) is a measure used in medical settings to quantify the extent of burns on a person’s body. It is calculated as the ratio of the burned area to the total body surface area, expressed as a percentage. Clinicians typically estimate %TBSA burned using standardized methods (for example, the Rule of Nines or a Lund–Browder chart), along with burn depth and location, to help guide care decisions.

How to Calculate Burn Percentage?

The following steps outline how to calculate the burn percentage from areas.

  1. Determine the total body surface area (TBSA) as an area value (commonly in m²).
  2. Estimate the burned area (BA) as an area value in the same units as TBSA.
  3. Calculate the burn percentage using the formula BP = (BA / TBSA) * 100.
  4. After inserting the values and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

Total Body Surface Area (TBSA) = 1.80 m²

Burned Area (BA) = 0.36 m²