Rule of Nines (Burns) Calculator

Rule of Nines (Burns) Calculator for Emergency. The sum is an area estimate only. It cannot determine burn depth, inhalation injury, the need for transfer or a resuscitation prescription. Compare region-level contributions with the examination to catch double counting before carrying a number into another calculation.

For shared guidance on choosing a tool and documenting results, read the clinical calculator workflow.

How this calculator works

Each adult region carries a fixed fraction of total body surface area. The form multiplies that fraction by the percentage of the region actually burned and then sums nonoverlapping contributions. Whole head/neck is 9%, each arm 9%, each leg 18%, anterior trunk 18%, posterior trunk 18% and perineum 1%. The complete set totals 100%.

When to use this calculator

Use for an approximate adult burn-area calculation after depth has been assessed. Count partial- and full-thickness injury; exclude superficial epidermal erythema. Every region is explicitly recorded, including zero for an unburned region, so absence of data cannot masquerade as an examined normal area.

Inputs used

  • Adult body proportions and partial/full-thickness burn depth confirmed?
  • Head and neck: fraction of this region burned (%)
  • Anterior trunk: fraction of this region burned (%)
  • Posterior trunk: fraction of this region burned (%)
  • Left arm: fraction of this region burned (%)
  • Right arm: fraction of this region burned (%)
  • Left leg: fraction of this region burned (%)
  • Right leg: fraction of this region burned (%)
  • Perineum: fraction of this region burned (%)

Clinical interpretation

The sum is an area estimate only. It cannot determine burn depth, inhalation injury, the need for transfer or a resuscitation prescription. Compare region-level contributions with the examination to catch double counting before carrying a number into another calculation.

Worked example

If the entire left arm and half the anterior trunk are burned, their contributions are 9 x 100/100 = 9% and 18 x 50/100 = 9%. With all other regions entered as zero, the estimate is 18% TBSA. Half an arm contributes 4.5%, not 50% of the whole body.

Limitations and safety notes

Adult proportions are approximate and are not age-adjusted for children. A detailed chart may be more appropriate for irregular distributions or unusual body proportions. This calculator does not display or reproduce an ABA body diagram, and source availability does not imply organizational endorsement. Decimal output reflects arithmetic, not equivalent measurement precision.

Frequently asked questions

What does 50 mean beside the anterior trunk?

It means half of that region, contributing 9% of adult TBSA.

Can superficial redness be included?

No. The burn-area convention used here excludes superficial epidermal injury.

Is the same anatomy appropriate for a young child?

No. Use an age-adjusted pediatric assessment, such as an appropriately sourced Lund-Browder chart.

References

  • ABA official guidance: adult regional TBSA proportions, burn-depth exclusions and pediatric differences; diagram not reproduced. https://www.ameriburn.org/burn-care-team/resources/guidelines-for-burn-patient-referral

Editorial review and citation methodology

Maintained by the Quick Medical Calculator Editorial Team. Content record date: September 9, 2026. A content date is not evidence of independent clinical review. Individual clinical sign-off is not recorded on this page.

  • Prefer original validation studies for scoring systems and prediction tools.
  • Use current specialty society guidance, transplant allocation policy, public health guidance, or regulator resources when they govern clinical use.
  • Include limitations and safety notes when a calculator is population-specific, context-dependent, or unsuitable as a standalone decision tool.

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