Burn Rule of Nines Calculator

Select burned body regions to instantly calculate the total body surface area (TBSA) percentage affected using the Rule of Nines.

Use the Burn Rule of Nines Calculator

Select Burned Regions

Check each body area that has been burned. Percentages are per the Rule of Nines for adults.

Anterior Trunk
Posterior Trunk
Arms (9% each)
Legs (18% each — split into thigh & lower leg)

Estimated TBSA Burned

0%

of total body surface area

0%50%100%
Select regions to begin

Rule of Nines Reference

Region TBSA
Head & Neck9%
Anterior Trunk (chest)9%
Anterior Trunk (abdomen)9%
Posterior Trunk (upper)9%
Posterior Trunk (lower)9%
Both Arms18%
Both Thighs18%
Both Lower Legs & Feet18%
Perineum1%
Total100%

Adult Burn Severity Guide

Minor — less than 10% TBSA. Outpatient treatment may be appropriate.
Moderate — 10%–25% TBSA. Hospital admission typically required.
Major / Critical — above 25% TBSA. Burn center referral strongly indicated.

This tool is for educational reference only. Always seek immediate professional medical care for burn injuries.

Summary

The Rule of Nines is a standardized method used in emergency medicine to rapidly estimate the percentage of an adult's body surface area (TBSA) affected by burns. Each major body region is assigned a value that is roughly a multiple of 9%: the head and neck account for 9%, each arm for 9%, the chest and abdomen each for 9% (totaling 18% for the anterior trunk), the upper and lower back each for 9% (totaling 18% for the posterior trunk), each thigh for 9% and each lower leg for 9% (totaling 18% per leg), and the perineum for 1%. This tool lets you select burned zones interactively and calculates the cumulative TBSA instantly.

How it works

  1. Check each burned body region using the list to mark it as affected.
  2. Each region contributes its fixed Rule of Nines percentage to the running total.
  3. The TBSA percentage updates instantly as you select or deselect regions.
  4. Review the severity classification (minor, moderate, major) shown alongside the TBSA.
  5. Use the Reset button to clear all selections and start over.
  6. Print or note the result to share with a medical professional.

Use cases

  • Emergency first-responder triage for adult burn victims.
  • Nursing and paramedic training on burn area estimation.
  • Medical student practice with the Rule of Nines algorithm.
  • Quick reference during burn unit patient intake.
  • Pre-hospital burn severity documentation.
  • Educational demonstrations in anatomy and trauma courses.

Frequently Asked Questions

Last updated: 2026-09-30 · Reviewed by Nham Vu