Body Surface Area Calculator
Body Surface Area (BSA) is an important measurement used in medicine to calculate drug dosages, determine cardiac index, and assess metabolic rates. BSA is considered a more accurate indicator of metabolic mass than body weight alone, making it essential in clinical pharmacology and oncology.
This calculator provides BSA estimates using two well-established formulas: the Mosteller formula (a simplified, widely-used approximation) and the Du Bois formula (the original 1916 formula still considered a gold standard). Enter your weight in kilograms and height in centimeters to get instant results.
How it works
Mosteller: BSA (m²) = √(height(cm) × weight(kg) / 3600). Du Bois: BSA (m²) = 0.007184 × height(cm)^0.725 × weight(kg)^0.425.
Use cases
- Calculating chemotherapy drug dosages based on BSA
- Determining cardiac index (cardiac output / BSA)
- Assessing metabolic rate and caloric needs in clinical settings
- Burn area estimation as a percentage of total BSA
Frequently asked questions
How do I calculate body surface area from height and weight?
The simplest way is the Mosteller formula: BSA (m²) = √(height in cm × weight in kg ÷ 3600). The Du Bois formula from 1916 uses exponents instead: 0.007184 × height^0.725 × weight^0.425. This calculator shows both results so you can compare them.
What is a normal body surface area for an adult?
An average adult BSA is roughly 1.7 m², with typical values closer to 1.9 m² for men and 1.6 m² for women. Your exact value depends on your height and weight, which is why clinicians calculate it individually instead of relying on averages.
Why is BSA used for chemotherapy dosing instead of body weight?
BSA correlates better with metabolic mass, blood volume, and organ function than weight alone, giving a more consistent basis for drug exposure. Many chemotherapy protocols express doses in mg per m² of body surface area, which oncologists then adjust for individual patient factors.
What is the difference between the Mosteller and Du Bois formulas?
Mosteller (1987) is a simplified square-root formula that is easy to compute and widely used in modern clinical practice. Du Bois (1916) is the original empirically derived formula and is still considered a gold standard. For most adults the two results differ only slightly, typically by a few percent.
Is body surface area the same as BMI?
No. BMI (weight ÷ height²) is a screening index for underweight, overweight, and obesity, while BSA estimates the total external surface of the body in square meters. BSA is used for drug dosing, cardiac index, and burn assessment, not for classifying body weight.