Calculate your body surface area (BSA) in square meters using 6 validated clinical formulas. BSA is used for chemotherapy dosing, anesthesia calculations, cardiac index, and other clinical applications where body weight alone is insufficient.
Your Body Surface Area
BSA (Mosteller)—
BSA (DuBois)—
vs. Average Adult (1.73 m²)—
Formula Average—
BSA Formula Comparison
Formula
BSA (m²)
Common Use
Clinical Applications of BSA
Application
Your Value
Notes
Why BSA Matters in Medicine
Body surface area correlates more closely than weight with several critical physiological parameters: glomerular filtration rate (GFR), cardiac output, and basal metabolic rate. This makes it the preferred dosing basis for drugs where precise exposure control is critical.
Formulas
Mosteller (1987): BSA = √(H(cm) × W(kg) / 3600) — most widely used today
Boyd (1935): Complex formula, accurate for extremes
All BSA formulas are estimates. True BSA can only be measured by direct methods (plaster cast, 3D scanning). Mosteller is recommended for most adult clinical applications due to its simplicity and acceptable accuracy.
Why Body Surface Area Is Used in Medicine
Body surface area (BSA) is used to calculate dosages for chemotherapy drugs, certain antibiotics, and other medications where weight alone provides insufficient accuracy. BSA-based dosing better accounts for differences in body composition. It is also used to assess burn coverage and estimate cardiac index.
The Mosteller formula (√(height cm × weight kg ÷ 3600)) is the most widely used in clinical practice due to its simplicity and accuracy. The DuBois formula, published in 1916, was historically dominant but is now largely replaced.
Frequently Asked Questions
Average BSA for adult men is approximately 1.9 m² and for women approximately 1.6 m². A 70 kg, 170 cm person has a BSA of about 1.82 m² using Mosteller. Pediatric doses are often scaled relative to a standard adult BSA of 1.73 m².
No single formula is universally superior across all body types. Mosteller is recommended by most oncology guidelines for adults. The Boyd formula is preferred for pediatric patients. For clinical decisions, always follow your healthcare provider's guidance.
Chemotherapy drugs are often dosed in mg/m². A drug at 100 mg/m² would be given as 182 mg to a patient with BSA 1.82 m². This approach aims for consistent drug exposure across patients of different sizes, though whether it actually reduces toxicity variability compared to flat dosing remains debated in research.
Height = 177.8 cm, Weight = 79.4 kg. Using the Mosteller formula: BSA = √(177.8 × 79.4 ÷ 3600) = √(3.921) = 1.980 m². The DuBois formula gives: 0.007184 × 177.8^0.725 × 79.4^0.425 = 0.007184 × 54.63 × 7.28 = 1.958 m². A chemotherapy drug dosed at 100 mg/m² would be administered at approximately 196–198 mg for this patient. Their BSA is about 14% above the 1.73 m² standard reference value.
Yes. In burn medicine, the extent of injury is expressed as a percentage of total BSA (TBSA). The Rule of Nines divides the body into areas each representing ~9% of BSA: head and neck (9%), each arm (9%), each leg (18%), front torso (18%), back torso (18%), and genitalia (1%). Burns covering more than 20% TBSA require fluid resuscitation calculated using Parkland formula: 4 mL × weight (kg) × %TBSA burned in the first 24 hours.