Body Surface Area (BSA) Calculator
Compute total anatomical surface area in square meters (m²) using validated clinical equations from Mosteller, Du Bois, and Haycock.
Body Surface Area (BSA) Calculator
Determine total external body surface area in square meters (m²) using Mosteller, Du Bois, and Haycock formulas.
√([wt × ht] / 3600)
0.007184 × wt^0.425 × ht^0.725
0.024265 × wt^0.5378 × ht^0.3964
Medical & Physiological Purpose of Body Surface Area:
Normal adult reference: ~1.7 m² (women) to ~1.9 m² (men). Unlike BMI or body fat percentage, Body Surface Area is not a direct measure of physical fitness, obesity, or aesthetic health. In medicine, BSA serves as a physiological indexing metric for glomerular filtration rate (eGFR in mL/min/1.73 m²), cardiac output index, and oncologic chemotherapy medication dosing.
Clinical Screening Reference & Medical Notice
Calculations provided on HOW WEIGHT are based on published statistical standards (such as WHO, CDC, and peer-reviewed metabolic equations) and are intended for educational and general screening purposes only.
They do not directly measure body fat distribution or visceral adipose tissue, nor do they replace personalized clinical diagnostic evaluation by a licensed healthcare provider. Learn more about our clinical methodology & disclaimers →
Clinical Methodology & Historical Equations
Body surface area correlates more strongly with metabolic turnover, renal clearance rates, and cardiac output than total body weight alone because heat dissipation and cellular respiration scale with surface area in mammalian biology (Rubner's surface law). In 1916, Delafield Du Bois and Eugene Du Bois published their landmark photographic coating technique, establishing the foundational power-law equation. In 1987, Dr. Robert Mosteller published his simplified square-root equation, which has since become the dominant standard in modern oncology and nephrology.
Mosteller Formula (1987)
Modern clinical gold standard for routine medication dosing, dialysis adequacy, and cardiac index normalization.
Du Bois & Du Bois (1916)
Classical non-linear allometric power law derived from direct planar surface measurements of cadavers and volunteers.
Haycock Formula (1978)
Developed specifically to improve surface area estimations across pediatric and low-birth-weight patient cohorts.
Worked BSA Calculation
For an individual weighing 72.0 kg (158.7 lbs) with a height of 175 cm (5 ft 9 in):
- Step 1: Multiply weight and height: 72 × 175 = 12,600.
- Step 2: Divide by 3600: 12,600 ÷ 3600 = 3.5.
- Step 3: Take the square root: √3.5 = 1.87 m² (Mosteller).
- Du Bois comparative value: 0.007184 × (72^0.425) × (175^0.725) = 1.87 m² (identical).
Frequently Asked Questions
What is Body Surface Area (BSA)?
Body Surface Area (BSA) is the measured or calculated total external surface area of a human body expressed in square meters (m²). It is widely used in clinical medicine to index physiological parameters and calculate drug dosages.
Is Body Surface Area a measure of physical fitness or body fat?
No. BSA is strictly a physiological indexing metric and is not a measure of physical fitness, aesthetic body composition, or adiposity. It reflects overall physical dimensions and metabolic surface area.
Why is the Mosteller formula preferred in clinical practice?
The Mosteller formula—BSA (m²) = √([weight in kg × height in cm] / 3600)—was introduced in 1987 in the New England Journal of Medicine. It is preferred because it is mathematically simple, easily computed, and produces results nearly identical to complex exponential formulas like Du Bois.
What is the average Body Surface Area for adults?
The average adult male has a BSA of approximately 1.9 m² (typically ranging between 1.8 and 2.1 m²), while the average adult female has a BSA of approximately 1.6 to 1.7 m².
How is BSA used in medicine?
BSA is used in oncology to calculate chemotherapy dosages with narrow therapeutic indices, in nephrology to normalize glomerular filtration rates (eGFR in mL/min/1.73 m²), in cardiology to index cardiac output (cardiac index in L/min/m²), and in critical care for burn fluid resuscitation protocols.