Body Surface Area (BSA) is the total surface area of the human body. In medical physiology and therapeutics, BSA is considered a more accurate indicator of metabolic mass than body weight alone. This calculator allows you to compute BSA using four of the most widely accepted formulas: Mosteller, Du Bois, Haycock, and Gehan & George. It is commonly used in clinical settings for calculating drug dosages, particularly in chemotherapy, and for assessing burn severity.
Features of This Calculator
Designed for accuracy and ease of use, our BSA Calculator offers robust features for medical professionals and students.
- Multi-Formula Support: Calculates BSA using the Mosteller (primary), Du Bois, Haycock, and Gehan & George formulas simultaneously for comparison.
- Unit Conversion: Seamlessly switch between Metric (cm/kg) and Imperial (ft/lb) units. The calculator automatically handles the conversions.
- Visual Indicator: Includes a visual bar to show where the calculated BSA falls relative to the average adult BSA (approx. 1.9 m²).
- Real-Time Calculation: Results update instantly as you type, allowing for quick adjustments and scenario planning.
Why is BSA Important?
BSA is a critical metric in several medical fields:
- Chemotherapy Dosing: Chemotherapeutic agents have low therapeutic indices. Dosing by BSA helps normalize metabolic clearance across patients of different sizes.
- cardiology: Cardiac Index (CI) is calculated by dividing Cardiac Output by BSA, providing a better assessment of heart function.
- Burn Assessment: The "Rule of Nines" and total body surface area burn percentage are crucial for fluid resuscitation planning.
- Renal Function: Glomerular Filtration Rate (GFR) is often normalized to a standard BSA of 1.73 m².
How to Use the BSA Calculator
- Select Your Unit: Choose between Metric (cm/kg) or Imperial (ft/lbs) at the top of the calculator.
- Enter Height: Input the patient's height. If using Imperial, you can enter feet and inches separately.
- Enter Weight: Input the patient's weight.
- Read Results: The BSA in square meters (m²) will appear below. The "Mosteller" result is highlighted as it is the most commonly used formula practical purposes.
Formulas Used
Here are the mathematical formulas used by this tool (W = Weight in kg, H = Height in cm):
- Mosteller: $\sqrt{\frac{H \times W}{3600}}$
- Du Bois: $0.007184 \times W^{0.425} \times H^{0.725}$
- Haycock: $0.024265 \times H^{0.3964} \times W^{0.5378}$
- Gehan & George: $0.0235 \times H^{0.42246} \times W^{0.51456}$
Note: The Mosteller formula is widely adopted due to its simplicity and because it provides results very similar to the more complex Du Bois formula.
Frequently Asked Questions (FAQs)
Q: What is the average BSA?
The average BSA is generally cited as 1.9 m² for adult men and 1.6 m² for adult women.
Q: Which formula should I use?
The Mosteller formula is the most popular for general clinical use. The Du Bois formula is the classic standard, often used as a reference. Always follow your institution's protocols.
Q: Why use BSA instead of weight?
Metabolic rate and blood volume are more closely related to surface area than to weight alone, especially in patients with abnormal body fat composition.
Final Words
The Body Surface Area Calculator is an indispensable utility for healthcare providers, ensuring accurate and safe dosing for patients. By aggregating the top formulas into one easy-to-use interface, it saves time and minimizes the risk of calculation errors. Always verify critical clinical calculations manually or with a secondary source.
