Free BSA calculator to compute body surface area in m² using Mosteller, Du Bois, Haycock, and Gehan-George medical formulas.
Mosteller (1987)
Simplified formula, widely accepted
You might also find these calculators useful
Body Surface Area is used in medicine to calculate drug dosages, determine burn severity, and assess body size. Our calculator supports multiple formulas including Mosteller (most common), Du Bois, Haycock, and more.
BSA measures total skin surface area in square meters. Unlike BMI, BSA accounts for both height and weight to estimate actual body size. Average adult BSA is 1.7-2.0 m². BSA is preferred over weight for dosing many medications because it better correlates with metabolic rate.
Mosteller Formula (Most Common)
BSA = √((Height × Weight) / 3600)Calculate appropriate medication doses.
Determine percentage of body affected.
Complement BMI with BSA measurement.
Mosteller is most widely used due to simplicity. Du Bois is the classic formula. Haycock is preferred for children. Your healthcare provider may specify which to use.
Average adult BSA is about 1.7 m² for women and 1.9 m² for men. Children have lower BSA proportional to their size. BSA typically ranges from 1.5-2.2 m² in adults.
BSA correlates better with blood volume, cardiac output, and organ size than weight alone. This provides more accurate dosing, especially for drugs with narrow safety margins like chemotherapy.
The 'Rule of Nines' divides body surface into percentages. BSA helps calculate fluid resuscitation needs—burns over 20% BSA require aggressive IV fluids using formulas like Parkland.