Body Surface Area Calculator
BSA Formulas
Du Bois & Du Bois (1916)
BSA = 0.007184 x H^0.725 x W^0.425
Mosteller (1987)
BSA = sqrt(H x W / 3600)
Haycock (1978)
BSA = 0.024265 x H^0.3964 x W^0.5378
Gehan & George (1970)
BSA = 0.0235 x H^0.42246 x W^0.51456
H = Height in cm, W = Weight in kg
Understanding Body Surface Area (BSA)
Body Surface Area (BSA) is a measurement of the total surface area of the human body. It is an important physiological measurement used in many medical applications, particularly in calculating drug dosages and assessing metabolic rates.
Medical Uses of BSA
- Chemotherapy dosing: Cancer drugs are often dosed per m2 of BSA
- Cardiac index: Cardiac output is normalized to BSA
- Renal function: GFR is often normalized to BSA
- Burn assessment: Extent of burns can be estimated using BSA
- Fluid resuscitation: Calculations based on BSA
Which Formula to Use?
| Formula | Best For |
|---|---|
| Du Bois | Most widely used, general adult population |
| Mosteller | Simple calculation, widely accepted |
| Haycock | Pediatric patients, infants to adults |
| Gehan & George | Alternative to Du Bois, similar accuracy |
Medical Disclaimer
This calculator is for educational purposes only. Drug dosing and medical decisions should always be made by qualified healthcare professionals. Never adjust medication dosages without consulting your doctor.
Frequently Asked Questions
What is body surface area (BSA) used for?
BSA is primarily used in medicine for calculating drug dosages, especially chemotherapy drugs, which are often dosed per square meter of body surface. It's also used to calculate cardiac index, normalize GFR measurements, assess burn area, and determine fluid resuscitation needs. BSA provides a more accurate measure than body weight alone for many medical calculations.
Which BSA formula is most accurate?
The Du Bois formula (1916) is most widely used and validated for adults. The Mosteller formula is simpler and produces similar results. For children and infants, the Haycock formula is often preferred. All formulas provide estimates within a few percent of each other for most individuals.
What is a normal body surface area?
Average adult BSA is approximately 1.7 square meters for women and 1.9 square meters for men. BSA typically ranges from 1.5 to 2.2 square meters in adults. Newborns have a BSA around 0.25 square meters. BSA varies with height and weight, so 'normal' depends on body size.
Why is BSA used instead of weight for drug dosing?
BSA correlates better than weight with many physiological parameters including cardiac output, blood volume, and metabolic rate. Drugs distribute through body fluids and tissues, which relate more closely to surface area than weight. This is especially important for drugs with narrow therapeutic windows like chemotherapy agents.