Body Surface Area Calculator

About Body Surface Area Calculator

Body Surface Area (BSA) is the measured or calculated surface area of a human body. For many clinical purposes, BSA is a better indicator of metabolic mass than body weight because it is less affected by abnormal adipose mass. BSA is used in various medical tasks including medication dosages, burn assessment, and chemotherapy regimens.

BSA Formulas

Several formulas have been developed over the years to estimate body surface area based on height and weight:

Du Bois Formula (1916)

BSA = 0.007184 × Height^0.725 × Weight^0.425

The Du Bois formula is one of the most widely used BSA formulas. It was derived from direct measurements of only 9 subjects.

Mosteller Formula (1987)

BSA = √(Height × Weight / 3600)

The Mosteller formula is simpler to calculate and is often used in clinical settings. It was derived as a simplification of the Du Bois formula.

Haycock Formula (1978)

BSA = 0.024265 × Height^0.3964 × Weight^0.5378

The Haycock formula was developed from measurements of 81 children and adults and is considered more accurate for pediatric patients.

Gehan & George Formula (1970)

BSA = 0.0235 × Height^0.42246 × Weight^0.51456

This formula was derived from measurements of 401 cancer patients and is sometimes used in oncology settings.

Clinical Importance

BSA is used to calculate medical indicators including:

• Cardiac index (CI = Cardiac Output / BSA)
• Chemotherapy dosages (many drugs are dosed per m²)
• Glomerular filtration rate (GFR) calculations
• Burn assessment (percentage of total BSA burned)
• Fluid resuscitation calculations

Limitations

While BSA is widely used, it has some limitations:

• Most formulas were derived from small sample sizes
• May not be accurate for extreme body types (very tall/short, obese/emaciated)
• Doesn't account for body composition differences
• May overestimate BSA in obese patients and underestimate in very lean patients