Body Surface Area (BSA) Calculator
BSA Results (m2, ft2, in2):
| Formula | m2 | ft2 | in2 |
|---|
Note: BSA estimates are approximations. Use them for guidance, but always apply clinical judgment
when making critical decisions.
(Du Bois, Mosteller, Haycock, Gehan & George, Boyd, Fujimoto, Takahira, Schlich.)
Body surface area (BSA) is a measure of the total area of the skin of a human body. The most common way to calculate BSA is by using the weight (kilograms) and height (centimeters) of an individual. However, other factors such as age, sex, and body type can also affect BSA.
What is BSA?
Body surface area (BSA), is the total surface area of ​​a human body. It is used in many medical tasks, including dosage calculations, lung function testing, and central venous catheterization.
Estimation of BSA is important for many clinical purposes because most medications are dosed per unit of body surface area. There are a number of ways to calculate BSA; the most common one uses the patient’s weight and height.
Origin of BSA Calculation
The concept of body surface area was first proposed by the French physician Nicolas Andry in 1701. In his book “Orthopaedia”, Andry suggested that the size of plaster casts used to treat broken bones should be proportional to the patient’s BSA.
Andry’s idea was later expanded upon by several other researchers, including James Wardrop in 1842 and D’Arcy Wentworth Thompson in 1917. However, it was not until 1977 that BSA was formally defined by DuBois and DuBois. There are a number of other formulas that can be used to calculate BSA, but the DuBois and DuBois formula is the most accurate. When using any of these formulas, it is important to remember that they are only estimates and should not be used for exact calculations.
Mosteller BSA Calculator
The Mosteller formula for calculating body surface area was first published in 1987 in the New England Journal of Medicine. The formula uses height and weight to calculate body surface area, and is still considered one of the most accurate methods for doing so.
The formula is as follows:
BSA = the square root of [height (in centimeters) x weight (in kilograms) / 3600].
To use the formula, simply plug in your height and weight, and then take the square root of the result. The Mosteller formula is a quick and easy way to accurately calculate body surface area.
BSA (m2) = √( [Height(cm) x Weight(kg) ]/ 3600 )
Dubois BSA calculator
The Dubois and Du Bois formula is a method used to calculate the surface area of the human body. The formula uses a person’s height and weight to estimate the surface area. The results of the Dubois and Du Bois formula have been found to be within 3-5% of the actual surface area of the human body.
The Dubois and Du Bois formula is a simple and easy way to estimate the surface area of a person. It is important to note that the results of the formula are only an estimate, and should not be used as a replacement for measuring the actual surface area of a person.
BSA (m2) = 0.007184 x Height(cm)0.725Â x Weight(kg)0.425
Other BSA formula
Gehan and George
BSA (m2) = 0.0235 x Height(cm)0.42246Â x Weight(kg)0.51456
Haycock
BSA (m2) = 0.024265 x Height(cm)0.3964Â x Weight(kg)0.5378
Â
| Name | Formula | Advantages | Limitations |
|---|---|---|---|
| Du Bois |
BSA = 0.007184 × W^0.425 × H^0.725
|
Historically one of the most widely used; validated across diverse groups. | May be less accurate in extreme body sizes (e.g., very obese or cachectic). |
| Mosteller |
BSA = 0.016667 × (W × H)^0.5
|
Simple, easy to memorize; popular in clinical settings. | Potential oversimplification for some subpopulations. |
| Haycock |
BSA = 0.024265 × W^0.5378 × H^0.3964
|
Validated across infants, children, and adults; good for pediatrics. | Less commonly used in standard adult practice than Du Bois or Mosteller. |
| Gehan & George |
BSA = 0.0235 × W^0.51456 × H^0.42246
|
Originally developed for oncology research; used in some chemo dosing. | May not be as widely adopted in general medical use as Du Bois/Mosteller. |
| Boyd |
BSA = 0.03330 × W^(0.6157 − 0.0188 × log10(W)) × H^0.3
|
Incorporates log term for weight, aiming for finer accuracy in extremes. | More mathematically complex; rarely done manually without software. |
| Fujimoto |
BSA = 0.008883 × W^0.444 × H^0.663
|
Derived from Japanese population data; good for certain Asian demographics. | May be less accurate for non-Asian populations. |
| Takahira |
BSA = 0.007241 × W^0.425 × H^0.725
|
Similar in form to Du Bois; also from Japanese demographic studies. | Limited widespread validation outside Asian groups. |
| Schlich |
Men: BSA = 0.000579479 × W^0.38 × H^1.24
Women: BSA = 0.000975482 × W^0.46 × H^1.08 |
Uses 3D body-scan data; distinct formulas for men vs. women. | Relatively new; less common in routine clinical use. |
Body Surface Area in Clinical Medicine
Body surface area (BSA) is a commonly used measurement in clinical practice to tailor various medical interventions, with particular emphasis on both cardiac performance and chemotherapy dosing. Instead of relying on total body weight, BSA approximates the body’s metabolically active surface, aiming for more precise drug administration and physiological assessments. For instance, BSA is used to calculate the cardiac index, which normalizes heart performance to a person’s size, and in chemotherapy dosing, where many treatment protocols historically rely on BSA-based calculations to guide drug levels.
However, despite the established tradition of using BSA in chemotherapy, some significant critiques remain. One argument concerns drugs that have a very narrow therapeutic index, meaning only a small difference exists between a helpful dose and a toxic one. In these cases, even slight inaccuracies in estimating BSA can result in doses that either fail to control disease or cause undue toxicity. BSA is also known to lose accuracy for individuals at extreme heights or weights, in whom body composition deviates significantly from the populations on which most BSA formulas were validated. As a result, in highly atypical cases, clinicians may turn to alternative measures—like the body mass index (BMI)—or deploy specialized dosing adjustments.
Nevertheless, BSA-based dosing still often yields more consistent and safer results than calculations based purely on total body weight alone, particularly for moderate builds. This relative consistency explains why so many oncologists and pharmacists retain BSA calculations in chemotherapy protocols. Ultimately, using BSA properly involves an awareness of its limitations as well as an understanding that each patient’s physiology may require dose modifications to address unique factors like organ function, comorbidities, and prior treatment tolerance. By recognizing both the advantages and the drawbacks of BSA-based dosing, clinicians can balance standard practices with individualized patient care to achieve safer, more effective outcomes.
Estimating glucocorticoid replacement therapy
Hydrocortisone dose in mg = 10-12mg/m2 (BSA estimate) in 2-3 divided doses
Hydrocortisone Dose (Du Bois BSA)
Calculated BSA (Du Bois): m2
| Dose Range | Daily Total |
|---|---|
| Low (10 mg/m2) | |
| High (12 mg/m2) |
Note: This calculator uses the Du Bois BSA formula:
BSA = 0.007184 × (Weight0.425) × (Height0.725)
Hydrocortisone dose is estimated at 10–12 mg/m²/day. Actual therapy must be guided by clinical judgment.
References
Du Bois, D. and Du Bois, E.F. (1916) A Formula to Estimate the Approximate Surface Area if Height and Weight Be Known. Archives of Internal Medicine, 17, 863-871.
Gehan EA, George SL. Estimation of human body surface area from height and weight. Cancer Chemother Rep. 1970 Aug;54(4):225-35.
Haycock GB, Schwartz GJ, Wisotsky DH. Geometric method for measuring body surface area: a height-weight formula validated in infants, children, and adults. J Pediatr. 1978 Jul;93(1):62-6.
Mosteller RD. Simplified calculation of body-surface area. N Engl J Med. 1987 Oct 22;317(17):1098.
Ulett, Mark A., "On Growth and Form (1917), by Sir D'Arcy Thompson". Embryo Project Encyclopedia (2010-06-27).
A collection of other useful medical calculators in clinical endocrinology.
