Burn Surface Area Calculator (Rule of Nines)

The Wallace Rule of Nines is a widely used method to quickly estimate Total Body Surface Area (TBSA) affected by burns. It divides the adult body into regions each representing approximately 9% (or multiples of 9%) of total surface area, with the genitalia accounting for 1%. It is used in emergency and triage settings to guide fluid resuscitation decisions.

Body proportions change significantly with age. In adults (≥14 years), the head accounts for 9% and each leg for 18%. In children (1–14 years), the head is proportionally larger (up to 18%) and the legs are smaller. In infants (<1 year), the head represents an even larger share of TBSA, and the leg percentages are reduced accordingly. Using age-adjusted values is critical for accurate burn assessment.

The Palmar Method estimates burn area using the patient's own palm (including fingers), which represents approximately 1% of their TBSA. It is most useful for irregular, patchy, or scattered burns where the Rule of Nines is harder to apply, or for very small and very large burns where more precision is needed.

Generally, burns covering more than 25% TBSA in adults or 20% in children are classified as major burns requiring hospital admission. Burns over 10% TBSA in any age group are considered moderate, while those under 10% are minor. Involvement of critical areas (face, hands, feet, genitalia) can escalate severity regardless of percentage.

The Parkland Formula estimates the intravenous fluid needed in the first 24 hours after a burn: 4 mL × body weight (kg) × %TBSA burned. Half is given in the first 8 hours post-burn, and the remainder over the following 16 hours. Accurate TBSA estimation is essential for correct fluid resuscitation and preventing shock.

No. Superficial first-degree burns (like mild sunburn) are typically excluded from TBSA calculations because they do not require fluid resuscitation and heal without intervention. Only partial-thickness (second-degree) and full-thickness (third-degree) burns are included in standard TBSA assessments.

No. This tool is intended for educational and reference purposes only. Accurate burn assessment requires direct clinical evaluation by trained medical professionals. Burn size, depth, location, patient comorbidities, and other factors must all be considered. Always consult burn specialists for treatment decisions.

Infants and young children have disproportionately large heads and smaller lower limbs compared to adults. The Rule of Nines is adjusted to reflect these anatomical differences — using adult percentages on a child would significantly underestimate head burns and overestimate leg burns, leading to incorrect fluid resuscitation volumes.