What Is the Body Surface Area Calculator?
The Body Surface Area (BSA) Calculator estimates the total surface area of a person's body. BSA is measured in square meters (m²) and is used in medical settings to calculate appropriate drug dosages, assess kidney and heart function, and evaluate burn severity. This calculator uses three common formulas: DuBois, Mosteller, and Haycock.
What This Calculator Does
Enter your weight and height. The calculator computes your BSA using three different formulas and provides an average result. Different formulas may give slightly different results, but they are generally comparable.
Inputs Required
- Weight: Your body weight in kilograms
- Height: Your height in centimeters
Outputs Provided
- Average BSA: The average of three formulas in m²
- DuBois BSA: Result using the DuBois formula
- Mosteller BSA: Result using the Mosteller formula
- Haycock BSA: Result using the Haycock formula
How the Calculation Works
The calculator uses three different mathematical formulas to estimate BSA. Each formula has been developed through research and is used in different clinical settings. The DuBois formula is the oldest and most widely used. The Mosteller formula is simpler and easier to calculate. The Haycock formula is often preferred for pediatric patients.
DuBois: BSA = 0.007184 × Weight^0.425 × Height^0.725
Mosteller: BSA = sqrt((Weight × Height) / 3600)
Haycock: BSA = 0.024265 × Weight^0.5378 × Height^0.3964
Where Weight is in kg and Height is in cm
How to Use the Calculator
- Enter your weight in kilograms
- Enter your height in centimeters
- View your BSA calculated using three different formulas
- Use the average or formula-specific result as needed
Example Calculation
A person weighing 70 kg and 175 cm tall:
- DuBois: 0.007184 × 70^0.425 × 175^0.725 = 1.84 m²
- Mosteller: sqrt((70 × 175) / 3600) = 1.85 m²
- Haycock: 0.024265 × 70^0.5378 × 175^0.3964 = 1.86 m²
- Average: 1.85 m²
Real World Scenarios
Chemotherapy Dosing
A cancer patient's BSA is calculated to determine the appropriate chemotherapy dose. Many cancer drugs are dosed based on BSA to ensure safe and effective treatment.
Burn Assessment
A burn victim's BSA is used to calculate the percentage of body surface affected and determine fluid replacement needs for treatment.
Kidney Function Assessment
BSA is used to normalize kidney function measurements (GFR) to allow comparison across individuals of different sizes.
Why This Calculation Matters
BSA is a more accurate measure of metabolic mass than weight alone. It accounts for both height and weight and correlates better with organ function and drug metabolism. Using BSA for drug dosing helps ensure appropriate treatment regardless of body size.
Common Mistakes to Avoid
- Using different formulas inconsistently: Stick with one formula for consistency in clinical settings
- Confusing BSA with BMI: BSA and BMI are different measures. BSA is used for drug dosing; BMI is used for weight classification
- Ignoring formula differences: Different formulas can give different results, especially for very large or very small individuals
- Using outdated measurements: Recalculate BSA if weight or height changes significantly
Frequently Asked Questions
What is a normal BSA? Average BSA for adults is 1.5-2.0 m². Children have smaller BSA. BSA varies with height and weight.
Which formula is most accurate? All three formulas are reasonably accurate. The DuBois formula is most commonly used. The Mosteller formula is simpler. The Haycock formula is preferred for children.
How is BSA used in medicine? BSA is used to calculate drug dosages, assess kidney and heart function, evaluate burn severity, and normalize metabolic measurements.