Calculate body surface area using Du Bois, Mosteller, Haycock, Gehan-George, and Boyd formulas. Compare BSA results for accurate drug dosing and clinical assessment.
The Body Surface Area (BSA) Calculator estimates the total surface area of the human body using several validated medical formulas. BSA is a critical measurement in medicine, particularly for calculating chemotherapy drug doses, determining cardiac output indices, estimating renal clearance, and setting burn treatment protocols. Unlike body weight alone, BSA accounts for both height and weight, providing a more accurate basis for physiological scaling.
This calculator implements five widely used BSA formulas — Du Bois & Du Bois (1916), Mosteller (1987), Haycock (1978), Gehan & George (1970), and Boyd (1935) — so you can compare results across methods. Each formula uses slightly different exponents and coefficients, reflecting different study populations and methodologies. In most clinical contexts, the Mosteller formula is preferred for its simplicity and accuracy, while the Du Bois formula remains the historical standard.
Average adult BSA ranges from approximately 1.7 to 2.0 m², though values vary considerably based on body habitus. Understanding your BSA can help you and your healthcare provider make more informed decisions about medication dosing and treatment planning.
BSA is fundamental to safe and effective medical care. Oncologists use BSA to calculate chemotherapy doses because drug clearance correlates better with surface area than weight alone. Cardiologists use BSA to normalize cardiac output and valve area measurements. Nephrologists reference BSA when calculating glomerular filtration rate. Burn specialists use BSA to estimate fluid resuscitation needs. This calculator helps you estimate your BSA using multiple validated formulas for comparison and clinical application.
Du Bois (1916): BSA = 0.007184 × W^0.425 × H^0.725. Mosteller (1987): BSA = √(H × W / 3600). Haycock (1978): BSA = 0.024265 × W^0.5378 × H^0.3964. Gehan & George (1970): BSA = 0.0235 × W^0.51456 × H^0.42246. Boyd (1935): BSA = 0.0003207 × W^(0.7285 − 0.0188 × log10(W)) × H^0.3. Where W = weight in kg, H = height in cm, BSA in m².
Result: BSA ≈ 1.98 m² (Mosteller)
Using the Mosteller formula: BSA = √(178 × 80 / 3600) = √(14240 / 3600) = √3.956 = 1.989 m². The Du Bois formula gives a similar result: BSA = 0.007184 × 80^0.425 × 178^0.725 ≈ 1.978 m². Both values are consistent and fall within the normal adult range of 1.7-2.0 m² for a male of this size.
Body surface area estimation dates back to 1879 when Meeh proposed the first formula relating surface area to body weight. The landmark Du Bois & Du Bois paper of 1916 established the methodology that most subsequent formulas would follow. Despite studying only 9 subjects, their formula proved remarkably durable and remained the clinical standard for decades. Later researchers including Boyd (1935), Gehan & George (1970), Haycock (1978), and Mosteller (1987) refined the approach using larger datasets and modern statistical methods.
BSA serves as a critical scaling factor in numerous medical applications. In oncology, BSA-based dosing is the standard method for calculating chemotherapy drug amounts, with even small errors potentially leading to significant toxicity or treatment failure. In cardiology, the cardiac index (cardiac output divided by BSA) normalizes heart function measurements across patients of different sizes. In nephrology, BSA is used to standardize glomerular filtration rate (GFR) to 1.73 m², the average adult BSA when the original GFR studies were conducted.
While all five formulas produce similar results for average-sized adults, they can diverge for individuals at the extremes of body size. For obese patients, the Du Bois formula may underestimate BSA compared to more recent formulas. For children, the Haycock formula tends to be more accurate because it was specifically validated in pediatric populations. The Mosteller formula offers the best balance of simplicity and accuracy for general adult use.
Pharmaceutical companies have historically used BSA as the primary parameter for scaling drug doses from animal studies to human trials. The principle is that BSA correlates with many physiological parameters including blood volume, cardiac output, and metabolic rate better than body weight alone. However, the field is increasingly recognizing the limitations of BSA-based dosing and exploring alternatives such as pharmacokinetic modeling and therapeutic drug monitoring.
Body surface area (BSA) is the total area of the external surface of the human body, measured in square meters. It matters clinically because many physiological processes — including heat loss, drug metabolism, and organ function — scale more closely with surface area than with body weight. BSA provides a more reliable basis for drug dosing, cardiac index calculation, and burn assessment.
No single formula is universally most accurate for all populations. The Mosteller formula is widely recommended for its simplicity and accuracy in adults. The Haycock formula performs well across age ranges including children. The Du Bois formula is the historical standard. For most clinical purposes, the formulas agree within 5%, and the choice often depends on institutional protocol.
Different researchers derived BSA formulas from different study populations, using different measurement techniques, at different times. Du Bois (1916) studied only 9 subjects using a surface coating method. Later researchers used larger and more diverse populations. Each formula reflects the specific regression analysis of its data set, leading to slightly different coefficients and exponents.
Oncologists multiply the BSA (in m²) by a standard dose per square meter to calculate the total drug dose for each patient. This approach adjusts for body size differences and aims to achieve consistent drug exposure across patients. However, BSA-based dosing is an approximation, and some newer protocols are moving toward pharmacokinetic-guided dosing for greater precision.
Direct BSA measurement is extremely difficult and impractical for clinical use. Historical methods involved wrapping the body in paper or foil and measuring the area. Modern 3D body scanning can provide direct measurements, but formulas remain the standard clinical approach due to their simplicity and adequate accuracy for medical applications.
Yes. BMI (Body Mass Index) is a ratio of weight to height squared, used primarily to classify weight status. BSA is an estimate of actual body surface area in square meters, used for clinical dosing and physiological scaling. They measure different things: BMI is a screening tool for weight classification, while BSA is a clinical parameter for treatment calculations.
Average adult BSA is approximately 1.7 m² for women and 1.9 m² for men. Normal ranges typically fall between 1.5 and 2.2 m², depending on body size. Very large individuals may have BSA values above 2.5 m², while petite adults may be below 1.5 m². Children and infants have proportionally larger BSA relative to their weight.
BSA changes with age primarily because body size changes. In children, BSA increases rapidly with growth. In adults, BSA remains relatively stable unless weight changes significantly. Elderly adults may experience slight decreases in BSA due to height loss from vertebral compression. The formulas themselves are age-independent — they use only height and weight.