Body Surface Area Calculator
Calculate your estimated body surface area using your height and body weight with the Mosteller formula.
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Your BSA Result
Body surface area, commonly abbreviated as BSA, is an estimate of the total external surface area of the human body. Unlike body weight alone, BSA takes both height and weight into account and is commonly expressed in square meters (m²).
What Is Body Surface Area?
Body Surface Area (BSA) is a measurement used to estimate how much surface area a person's body has. It is different from body mass because two people with the same weight can have different body surface areas depending on their height and body proportions.
BSA is usually calculated using a person's height and weight. The result is expressed in square meters (m²). Several mathematical formulas can be used, with the Mosteller formula being one of the simplest and most widely used methods.
Why Is Body Surface Area Important?
BSA can be useful in healthcare and scientific settings because some physiological measurements are influenced by body size. It provides another way of describing body size alongside measurements such as weight, height, BMI and body composition.
Body Size Estimate
BSA combines height and weight into one estimated measurement of body surface area.
Clinical Calculations
BSA is sometimes used as a reference in medical calculations and clinical research.
Body Measurements
BSA can complement other measurements when evaluating body size and physiological characteristics.
How Is Body Surface Area Calculated?
One of the most commonly used equations for estimating BSA is the Mosteller formula. It uses height in centimeters and weight in kilograms.
The resulting value is expressed in square meters (m²). For example, if a person is 175 cm tall and weighs 70 kg, the calculation produces an estimated BSA of approximately 1.84 m².
Body Surface Area Calculation Example
Height = 175 cm
Weight = 70 kg
BSA = √[(175 × 70) ÷ 3600]
Estimated BSA ≈ 1.84 m²
This example shows why both height and weight are needed. Changing either measurement changes the estimated body surface area.
Body Surface Area vs. BMI
BSA and BMI are both calculated using height and weight, but they answer different questions. BMI is mainly used as a weight-for-height screening measure, while BSA estimates body surface area.
| Measurement | Main Purpose | Typical Unit |
|---|---|---|
| Body Surface Area | Estimates total body surface area | m² |
| BMI | Weight-for-height screening measure | kg/m² |
| Body Weight | Measures total body mass | kg or lb |
What Factors Affect Body Surface Area?
The two main inputs used by the Mosteller BSA equation are height and body weight. As either measurement increases, estimated BSA generally increases as well.
- Height: Taller individuals generally have a larger estimated body surface area.
- Weight: Higher body weight generally increases the estimated BSA.
- Body proportions: Mathematical formulas provide estimates and do not directly measure individual body shape or actual skin surface.
How to Use the Body Surface Area Calculator
Using the calculator above is simple. Enter your height and current body weight, select the appropriate units, and calculate your estimated BSA.
For the most useful result, make sure your measurements are reasonably accurate and that you select the correct units. The calculator converts the values as needed before applying the BSA formula.
If you are exploring your overall body measurements, you can also compare your result with other tools such as the BMI Calculator or the Ideal Weight Calculator .
Limitations of Body Surface Area Calculations
BSA equations are mathematical estimates rather than direct measurements. Different formulas can produce slightly different results for the same person.
BSA should therefore be interpreted in context rather than treated as a precise measurement of health, fitness or body composition. It also does not tell you how much body fat, muscle or lean tissue you have.
Body Surface Area Calculator FAQs
What is a normal body surface area?
There is no single normal BSA value for everyone. Body surface area varies according to height, weight, age, sex and body size. Adults commonly have BSA values around the general range of roughly 1.5 to 2.2 m², although individual values can fall outside this range.
What does BSA mean?
BSA stands for Body Surface Area. It is an estimated measurement of the body's external surface area and is usually expressed in square meters.
What formula does this calculator use?
This calculator uses the Mosteller formula: BSA = √[(height × weight) ÷ 3600], with height in centimeters and weight in kilograms.
Is BSA the same as BMI?
No. BMI and BSA are different measurements. BMI is a weight-for-height screening measure, while BSA estimates body surface area.
Can BSA tell me if I am healthy?
No. BSA is not a standalone measure of health or fitness. It should be considered alongside other relevant measurements and, when appropriate, professional advice.
Is the Body Surface Area Calculator accurate?
It provides an estimate based on a mathematical formula. Different BSA equations may produce slightly different results, so the result should be viewed as an estimate rather than a direct measurement.
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