Calculators · General Surgery · Formula

Burn TBSA — Wallace Rule of Nines (adult)

Also called Rule of nines, Wallace rule of nines, TBSA burn

Percentage of total body surface area burned in adults, from the share of each body region involved.

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Formula and scoring

Adult: head and neck 9, each upper limb 9, anterior trunk 18, posterior trunk 18, each lower limb 18, perineum 1 (total 100). TBSA = Σ region weight × fraction of region burned.

Exam and ward pearls

  • Superficial (first-degree) erythema is excluded from %TBSA.
  • For small or scattered burns use the patient’s palm (≈1% TBSA); in children use the Lund–Browder chart because the head is relatively larger.

When not to rely on it

  • Adults only. The rule tends to overestimate TBSA in obese patients and is inaccurate in children (the head is about 18% in infants).

Source

  1. Wallace AB. The exposure treatment of burns. Lancet. 1951;1(6653):501-4. doi:10.1016/s0140-6736(51)91975-7 · PMID 14805109
  2. Smith I, Kidd S, Kim S, Tennill RM. Assessment and management of electrical injuries in adults in the emergency department. Cureus. 2026;18(4):e107162 (rule-of-nines regional percentages). doi:10.7759/cureus.107162 · PMID 42147553
  3. Broadis E, Chokotho T, Borgstein E. Paediatric burn and scald management in a low resource setting: a reference guide and review. Afr J Emerg Med. 2017;7(Suppl):S27-S31 (rule of nines in children; palm/hand method). doi:10.1016/j.afjem.2017.06.004 · PMID 30505671

Formula and cut-offs checked against these sources on 8 Nov 2026. Educational tool for clinicians; it does not replace clinical judgement.

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