What is Body Surface Area (BSA)?

Body Surface Area (BSA) is the total surface area of the human body, measured in square metres (m²). It is used in medical contexts to calculate drug doses, especially chemotherapy agents and cardiac medications, because certain physiological variables correlate better with surface area than body weight. Average adult BSA is approximately 1.6–1.9 m².

Which BSA formula is most accurate?

The Mosteller formula (√[Height(cm) × Weight(kg) / 3600]) is widely used for its simplicity and accuracy and is recommended by major oncology organisations. The DuBois & DuBois formula is the oldest and most historically used. Haycock is preferred for paediatric calculations. For most adults, all formulas give similar results within 5%.

What is the average adult BSA?

Average adult BSA is approximately 1.7–1.9 m² for men and 1.6–1.8 m² for women. Standard oncology chemotherapy doses are often calculated assuming a reference BSA of 1.73 m². BSA increases with height and weight.

Body Composition

Body Surface Area Calculator

Calculate your Body Surface Area (BSA) in m² using five validated formulas — DuBois, Mosteller, Haycock, Gehan-George, and Boyd. Supports metric (kg/cm) and imperial (lbs/inches).

BSA Calculator

Five validated formulas compared

Unit System

Weight (kg)

Height (cm)

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BSA — Mosteller Formula (Recommended)

Reference: 1.73 m² (standard clinical reference)

Body Surface Area is used in medicine to calculate drug doses (especially chemotherapy), assess cardiac output, set dialysis parameters, and determine burn area coverage. Average adult BSA is around 1.7–1.9 m² — larger than most people expect.

BSA Formula Comparison

Formula	Year	Best For
Mosteller	1987	Adults — simple, widely used in oncology
DuBois & DuBois	1916	Historical standard, adults
Haycock	1978	Paediatrics and children
Gehan & George	1970	General adult population
Boyd	1935	Wide weight range

Why Body Surface Area Is Used in Medicine

BSA-based drug dosing corrects for the enormous variation in body size between patients. A child and an adult have dramatically different metabolic rates and organ function; dosing by body weight alone is less precise than dosing by surface area for drugs with narrow therapeutic windows. Chemotherapy in particular uses BSA dosing because anti-cancer drugs affect rapidly dividing cells throughout the body — and the total mass of such cells correlates better with BSA than weight.

Frequently Asked Questions

BSA is primarily used for calculating medication doses — particularly chemotherapy, where fixed mg/m² dosing is standard. It also appears in cardiac physiology (cardiac index = cardiac output/BSA), burn medicine (estimating % of body surface burned), and renal medicine (GFR normalisation). Average adult BSA is 1.73 m², used as a reference for standardising many physiological measurements.

The Mosteller formula is recommended for most adults — it is simple (√[H×W/3600]), widely validated, and endorsed by major oncology organisations. For children, Haycock is preferred. For historical comparisons, DuBois is used. All five formulas in this calculator give results within 5% of each other for most adults.

No. BMI (kg/m²) is a ratio comparing weight to height squared, not an actual surface measurement. BSA (m²) is the estimated total skin surface area of the body, calculated from both height and weight using exponential formulas. BSA is used in clinical medicine for drug dosing, while BMI is a population health screening tool.

No — both give the same BSA result. Select Metric (kg/cm) or Imperial (lbs/inches) at the top of the calculator. The tool converts your inputs to metric units internally before applying the BSA formulas. The output is always in m² (square metres), which is the universal clinical standard.

Body Surface Area Calculator

BSA Calculator

BSA Formula Comparison

Why Body Surface Area Is Used in Medicine

Frequently Asked Questions

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