Body Surface Area Calculator
Calculate your BSA in square meters
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What Is Body Surface Area?
Body Surface Area (BSA) is the total surface area of the human body measured in square meters. It provides a more accurate representation of metabolic mass than body weight alone because it accounts for both height and weight proportionally. BSA is widely used in clinical medicine, pharmacology, and physiology to calculate drug dosages, assess metabolic rate, and evaluate organ function.
The concept of BSA was first introduced in the early 1900s and has since become a standard measurement in healthcare. The average adult male BSA is approximately 1.9 m², while the average adult female BSA is approximately 1.6 m². These values vary significantly with height, weight, age, and body composition.
How BSA Is Used in Medicine
BSA is used in numerous clinical applications, most notably for calculating chemotherapy dosages. Many cytotoxic drugs are prescribed on a per-square-meter basis to ensure proportional dosing across patients of different sizes. This approach minimizes the risk of underdosing in smaller patients and overdosing in larger ones.
- Drug dosing — Chemotherapy, cardiac medications, and pediatric drugs are often dosed per m² of BSA.
- Burn assessment — The Rule of Nines and Lund-Browder chart use BSA to estimate burn severity.
- Cardiac index — Cardiac output is divided by BSA to calculate cardiac index, a key heart function metric.
- GFR estimation — Glomerular filtration rate uses BSA to normalize kidney function measurements.
Average BSA by Gender and Size
BSA varies significantly between individuals based on their body proportions. The Mosteller formula, which this calculator uses as its primary method, is the simplest and most widely accepted BSA estimation: BSA (m²) = v((height cm × weight kg) / 3600). This formula provides reliable estimates for the majority of the population.
The DuBois formula offers an alternative calculation that may be slightly more accurate at extreme body sizes: BSA = 0.007184 × height^0.725 × weight^0.425. Both formulas are included in this calculator so you can compare results and see the range of estimated values. Consult your healthcare provider for clinically precise BSA measurements. You can also check your BMI and body fat percentage for a complete health picture.
Frequently Asked Questions
What is a normal BSA?
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Does BSA change with age?
How does BSA affect medication dosing?
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