Body Surface Area Calculator
Calculate body surface area (BSA) in square meters using multiple medical formulas. BSA is used for medication dosing, cardiac index and burn assessment.
How to use the Body Surface Area Calculator
- Enter your inputs into the Body Surface Area Calculator above.
- Results update instantly as you type — no submit button needed.
- Adjust any value to see how the result changes in real time.
The BSA formulas
Mosteller: BSA = √((H · W) / 3600) · · · DuBois: BSA = 0.007184 × H^0.725 × W^0.425
H is height in cm, W is weight in kg. Mosteller is the most commonly used in clinical practice because it's easy to compute. DuBois and Haycock provide slightly different estimates.
Worked example
A 75 kg adult at 178 cm by Mosteller: BSA = √((178 × 75)/3600) = √3.708 ≈ 1.93 m². By DuBois: 0.007184 × 178^0.725 × 75^0.425 ≈ 1.92 m². Results agree closely for typical adults.
Frequently asked questions
What is BSA used for?
Chemotherapy dosing (most cytotoxic drugs are dosed by BSA), cardiac index (cardiac output normalized to BSA), burn percentage assessment and pediatric drug dosing.
Are the formulas interchangeable?
Within ~3% for most adults. For extreme body sizes or pediatric patients, the formulas can diverge meaningfully. Hospitals usually standardize on one (often Mosteller) for consistency.
Does BSA change with weight loss?
Yes — BSA falls roughly with the 0.4 power of weight. A 10% weight loss reduces BSA by about 4%. Medications dosed by BSA may need adjustment.