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Printed on 6/29/2026
For informational purposes only. This is not medical advice.
The Rule of Nines is a clinical method for rapidly estimating the total body surface area (TBSA) affected by burns in adult patients. It divides the body into regions, each representing approximately 9% (or multiples of 9%) of the total body surface area: head and neck 9%, each upper limb 9%, anterior trunk 18%, posterior trunk 18%, each lower limb 18%, and perineum 1%. Accurate TBSA estimation is critical for guiding fluid resuscitation (Parkland formula), transfer decisions, and prognosis. This calculator allows entry of the burn percentage for each body region. Use the TBSA result to calculate IV fluid requirements with [Parkland Formula Calculator](/tools/parkland-formula). Monitor hemodynamic response with [MAP Calculator](/tools/map-calculator). Track organ dysfunction in major burns with [SOFA Score](/tools/sofa-score) and [APACHE II](/tools/apache-ii). Monitor AKI with [eGFR Calculator](/tools/egfr-calculator).
Formula: Total TBSA (%) = sum of all affected body region percentages. Maximum 100%.
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Only second-degree (partial-thickness) and third-degree (full-thickness) burns are included in TBSA. First-degree burns showing erythema only (like mild sunburn) are excluded from fluid resuscitation calculations.
For each body region, enter the estimated percentage of that region's surface area that is burned. For small, scattered burns, use the patient's palm (including fingers) as approximately 1% TBSA for reference.
The total TBSA drives fluid resuscitation: Parkland formula = 4 mL × body weight (kg) × %TBSA of lactated Ringer's solution in the first 24 hours. Half is given in the first 8 hours (from injury, not arrival). Use the result with [Parkland Formula Calculator](/tools/parkland-formula).
Emergency physicians, trauma surgeons
Rapid TBSA estimation determines resuscitation requirements, burn center transfer criteria, and prognostic category within the first hour. ABA criteria mandate transfer for burns >10% TBSA, full-thickness burns, and burns of face/hands/feet/genitals.
Paramedics, EMTs, flight nurses
Field TBSA estimation guides initial fluid administration and transport destination decisions. Early accurate estimation prevents both under-resuscitation and fluid overload, both of which worsen outcomes in major burns.
Burn surgeons, burn nurses
TBSA is used daily to calculate Parkland formula fluids, adjust for body weight, and monitor urine output targets (0.5 mL/kg/hr). Track organ dysfunction with [SOFA Score](/tools/sofa-score) and [APACHE II](/tools/apache-ii) in major burns.
Burn physicians, intensivists
The Baux score (age + %TBSA) and revised Baux score (age + %TBSA + 17 for inhalation injury) estimate mortality. Accurate TBSA is therefore critical not just for acute management but for family counseling and goals-of-care discussions.
ICU nurses, intensivists
In major burns (>30% TBSA), hourly fluid titration based on urine output (targeting 0.5–1 mL/kg/hr) and hemodynamic response requires accurate initial TBSA. Monitor renal function with [eGFR Calculator](/tools/egfr-calculator) for AKI detection.
Medical students, emergency medicine residents
The Rule of Nines is a core emergency medicine skill. The simple 9-based regional breakdown is designed for rapid recall under pressure, making it a foundational teaching tool for burn management.
Only partial-thickness (second-degree) and full-thickness (third-degree) burns are included in the TBSA calculation for the Parkland formula. Erythema alone from sunburn or brief contact is excluded.
For irregular or scattered burns, the patient's palm including fingers represents approximately 1% of their TBSA. This provides a portable reference for small burn estimation at the bedside or in the field.
Children have proportionally larger heads (18% at birth vs 9% in adults) and smaller legs. Use the Lund-Browder chart for all pediatric burn assessments to avoid significant underestimation of head burns and overestimation of leg burns.
Half the 24-hour Parkland volume is given in the first 8 hours — counted from the time of injury, not time of hospital arrival. Account for any pre-hospital fluids already received. Calculate with [Parkland Formula Calculator](/tools/parkland-formula).
Don't give Parkland fluids as a rigid schedule. Use urine output 0.5–1.0 mL/kg/hr as the endpoint and adjust infusion rate accordingly. Excessive fluid resuscitation causes abdominal compartment syndrome, pulmonary edema, and 'fluid creep.'
The presence of inhalation injury (carbonaceous sputum, singed nasal hairs, circumoral burns, stridor) adds approximately 17 points to the Baux score, equivalent to an additional 17% TBSA in terms of mortality impact. Secure the airway early.
Studies show emergency physicians and even burn surgeons overestimate TBSA by 50–100% on average. Overestimation leads to fluid overload. When uncertain, use the palm method and err toward conservative estimation initially, then reassess.
Transfers are indicated for >10% TBSA partial-thickness, any full-thickness burn, burns of face/hands/feet/genitals/major joints, circumferential burns, chemical and electrical burns, inhalation injury, and burns in patients with significant comorbidities regardless of size.
The Rule of Nines was described by Wallace (1951) and the Parkland formula by Baxter and Shires (1968). The American Burn Association 2022 Practice Guidelines provide current evidence-based recommendations for fluid resuscitation, transfer criteria, and burn center care standards.
Your total body surface area (TBSA) burn percentage is the sum of all affected body regions and represents the overall extent of burn injury. Burns affecting less than 10% TBSA in adults are generally considered minor and may be managed on an outpatient basis if they are superficial partial-thickness burns in non-critical areas. Burns covering 10% to 20% TBSA are considered moderate and typically require inpatient care with IV fluid resuscitation.
Burns exceeding 20% TBSA in adults (or 10% in children and elderly patients) are classified as major burns and require aggressive fluid resuscitation, typically calculated using the Parkland formula: 4 mL of lactated Ringer's solution per kilogram of body weight per percentage of TBSA burned, with half given in the first 8 hours and the remainder over the next 16 hours. These patients should be transferred to a verified burn center.
The TBSA percentage also has prognostic significance. Along with patient age and the presence of inhalation injury, TBSA is a key predictor of mortality. The Baux score (age + %TBSA) and revised Baux score provide mortality estimates. Accurate TBSA assessment is therefore critical not only for acute management but also for prognostication and family counseling.
The Rule of Nines should be used for rapid initial assessment of burn extent in adult patients presenting to the emergency department or at the scene of injury. It is most appropriate for medium to large burns where a quick TBSA estimate is needed to initiate fluid resuscitation and determine the need for burn center transfer. The American Burn Association transfer criteria include burns greater than 10% TBSA, among other factors.
This calculator is also useful when calculating fluid resuscitation requirements using the Parkland formula or other resuscitation protocols. Having an accurate TBSA estimate within the first hour of presentation is essential because delayed or inadequate fluid resuscitation worsens outcomes in major burns.
The Rule of Nines is designed for adult body proportions and is inaccurate for children, who have proportionally larger heads and smaller limbs. For pediatric patients, the Lund-Browder chart provides age-adjusted body surface area percentages and should be used instead. The Rule of Nines is also less accurate in obese patients, whose body proportions differ from the standard model.
This method estimates only the extent of the burn, not the depth. Burn depth (superficial, partial-thickness, or full-thickness) is a critical determinant of treatment and prognosis that requires separate clinical assessment. Only second-degree (partial-thickness) and third-degree (full-thickness) burns should be included in the TBSA calculation for fluid resuscitation — first-degree (superficial) burns are excluded.
TBSA estimation using the Rule of Nines has significant inter-rater variability, with studies showing that clinicians frequently overestimate burn size, particularly for scattered or irregularly shaped burns. Overestimation leads to excessive fluid resuscitation, which can cause complications such as abdominal compartment syndrome and pulmonary edema. For small or scattered burns, using the patient's palm (approximately 1% TBSA) as a reference may be more accurate.
Disclaimer: This tool is for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider with questions about your health.
April 21, 2026 · trust-baseline
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OpenDermatologyEstimate total body surface area (TBSA) burned using the Rule of Nines. Head=9%, each arm=9%, each leg=18%, torso=36%. Burns ≥20% TBSA require IV fluid resuscitation with the Parkland formula.
OpenEmergencyCalculate IV fluid requirements for burn patients using the Parkland formula: 4 mL × kg × % TBSA in 24 hours. Half given in first 8 hours from injury, half over next 16 hours.
OpenSelect which body regions are burned (Rule of Nines).