Body Surface Area (BSA) Calculator

Understanding Body Surface Area (BSA)

Body Surface Area (BSA) is a measurement of the total surface area of the human body. It is a more accurate indicator of metabolic mass than body weight because it is less affected by abnormal adipose mass. BSA is widely used in medicine for various calculations, including drug dosing, renal clearance estimation, and burn injury assessment.

The Mosteller Formula

This calculator uses the Mosteller formula, one of the most commonly used methods for calculating BSA:

BSA (m2) = Square Root of [(Height (cm) x Weight (kg)) / 3600]

The Mosteller formula was developed in 1987 and is widely accepted due to its simplicity and accuracy. It provides results comparable to more complex formulas while being easier to calculate.

Medical Applications of BSA

Chemotherapy Dosing

BSA is the standard method for calculating chemotherapy drug doses. Most cytotoxic drugs are dosed in mg/m2 to optimize efficacy while minimizing toxicity across patients of different sizes.

Burn Assessment

In burn injury assessment, BSA helps determine the percentage of total body surface affected, which is critical for fluid resuscitation calculations and treatment planning.

Cardiac Index Calculation

BSA is used to calculate the cardiac index (cardiac output divided by BSA), which provides a normalized measure of heart function accounting for body size.

Normal BSA Values

• Average adult male: 1.9 m2
• Average adult female: 1.6 m2
• Newborn: 0.25 m2
• 2-year-old child: 0.5 m2
• 10-year-old child: 1.14 m2

Alternative BSA Formulas

While the Mosteller formula is widely used, other formulas exist:

• Du Bois formula: BSA = 0.007184 x Weight(kg)^0.425 x Height(cm)^0.725
• Haycock formula: BSA = 0.024265 x Weight(kg)^0.5378 x Height(cm)^0.3964
• Gehan and George formula: BSA = 0.0235 x Weight(kg)^0.51456 x Height(cm)^0.42246