Calculate body surface area (BSA) using multiple validated formulas including Du Bois, Mosteller, Haycock, and other clinical formulas. Used for medical dosing and metabolic calculations.
Body Surface Area (BSA) is a measurement that refers to the total surface area of the human body. It is commonly used in medical settings because it provides a more accurate indicator of metabolic mass compared to body weight alone. BSA is particularly important for calculating medication dosages, especially in chemotherapy, and for various clinical assessments.
BSA is often used instead of body weight because it correlates better with many physiological processes such as cardiac output, glomerular filtration rate, and metabolic rate. It provides a more accurate basis for calculating drug dosages that have narrow therapeutic windows.
Where W = weight in kg, H = height in cm
Where H = height in cm, W = weight in kg
Validated in infants, children, and adults
Alternative formula for clinical use
Based on 3D body scan measurements
| Population | BSA (m²) | BSA (ft²) | Typical Weight Range |
|---|---|---|---|
| Newborn | 0.25 | 2.69 | 3-4 kg (6.6-8.8 lbs) |
| 2-year-old child | 0.5 | 5.38 | 12-14 kg (26-31 lbs) |
| 10-year-old child | 1.14 | 12.27 | 32-40 kg (70-88 lbs) |
| Adult female | 1.6 | 17.22 | 50-70 kg (110-154 lbs) |
| Adult male | 1.9 | 20.45 | 70-85 kg (154-187 lbs) |
Oncology: BSA-based dosing is the gold standard for most chemotherapy agents. It helps ensure that patients receive doses that are both effective and safe, regardless of their size.
Cardiology: Cardiac index (CI = cardiac output ÷ BSA) is used to assess heart function. Normal CI is 2.5-4.0 L/min/m². BSA is also used in echocardiography for indexing heart chamber sizes.
Nephrology: Kidney function tests like GFR are standardized to 1.73 m² BSA to allow comparison between patients of different sizes.
Pediatrics: BSA is particularly important in children as it provides better dosing accuracy than weight-based calculations for many medications.
| Measurement | Best Use | Advantages | Limitations |
|---|---|---|---|
| Body Surface Area | Drug dosing, metabolic calculations | Correlates with metabolic rate | Complex calculation |
| Body Weight | Simple drug dosing, general health | Easy to measure and calculate | Doesn't account for body composition |
| BMI | Population health screening | Standardized, easy to calculate | Doesn't reflect body composition |
| Lean Body Mass | Precise drug dosing, research | Accounts for body composition | Requires specialized measurement |
Measurement Precision: Accurate height and weight measurements are crucial for precise BSA calculations. Small errors in measurement can significantly affect dosing calculations.
Formula Selection: Different formulas may give slightly different results. The Du Bois formula is most widely used, but other formulas may be more appropriate for specific populations.
Clinical Context: Consider the specific clinical application when interpreting BSA results. What's appropriate for chemotherapy dosing may differ from cardiac assessments.
Obese Patients: In severely obese patients, some clinicians use adjusted body weight or lean body mass instead of actual weight for BSA calculations to avoid overdosing.
Pediatric Patients: Children have different body proportions than adults, but most BSA formulas have been validated for use in pediatric populations.
Elderly Patients: Age-related changes in body composition may affect BSA accuracy, but the formulas remain clinically useful.