Body Surface Area (BSA) Calculator
Calculate total surface area of the human body for clinical dosing and physiological assessment.
What is Body Surface Area (BSA)?
Body Surface Area (BSA) is the measured or calculated surface of a human body. In clinical medicine, BSA is often considered a more accurate indicator of metabolic mass than body weight because it is less affected by abnormal adipose tissue (body fat).
This metric is critical in various medical fields, particularly in oncology for determining chemotherapy dosages, in cardiology for indexing cardiac output, and in nephrology for normalizing glomerular filtration rates (GFR).
Common BSA Formulas Used
Medical professionals use several validated mathematical models to estimate BSA. Our calculator provides results for the three most widely accepted formulas:
- Mosteller Formula: The most commonly used formula due to its simplicity. It is calculated as the square root of (Height x Weight / 3600).
- Du Bois Formula: One of the oldest and most cited formulas in medical literature.
- Haycock Formula: Frequently utilized in pediatrics for infants and children.
Why BSA Matters in Clinical Practice
Using weight alone to determine drug dosages can lead to under-dosing in tall, thin patients or over-dosing in short, obese patients. BSA provides a "normalization" factor that accounts for the relationship between height and weight. For example, a "normal" adult BSA is generally considered to be 1.73 m².
BSA Calculation Examples
| Patient Type | Height/Weight | Approx. BSA |
|---|---|---|
| Average Adult Male | 178 cm / 80 kg | 1.99 m² |
| Average Adult Female | 163 cm / 65 kg | 1.71 m² |
| Child (10 years) | 138 cm / 32 kg | 1.11 m² |
Important Considerations
While BSA is a standard tool, clinical judgment is always paramount. Specific medications may require adjustments based on renal function, hepatic health, or specific BMI categories. Always consult with a healthcare professional for clinical decision-making.