Body Surface Area Calculator
Calculate your estimated body surface area from height and weight.
Understanding Body Surface Area Calculator
Body Surface Area (BSA) is an estimate of the total surface area of the human body and is commonly expressed in square meters (m²). Unlike body weight or Body Mass Index (BMI), BSA combines height and weight to produce a value that can be used as a general representation of body size. BSA is particularly useful in clinical and physiological calculations because some measurements and medical formulas are better expressed relative to body surface area than to body weight alone.
One of the most widely used methods for estimating BSA is the Mosteller formula. It uses height in centimeters and body weight in kilograms and produces a simple estimate of body surface area. Other formulas, including the Du Bois and Du Bois equation, have also been used in medicine and research. Because these equations were developed using different populations and mathematical approaches, their results can differ slightly. The Mosteller equation is popular because it is straightforward to calculate and is practical for routine clinical use.
Making the inputs meaningful
Body Surface Area Calculator is most useful when the measurements you enter are taken using the same units and definitions shown beside each field. The calculator asks for values such as Height (cm), Weight (kg); enter the measurements as accurately and consistently as possible rather than rounding them before calculation.
What this calculation can and cannot tell you
The number produced by this tool should be read in the context of the inputs and the method used by the calculator. A calculated health or fitness figure can be useful for education, planning, or tracking change over time, but it does not by itself describe every aspect of an individual’s health.
About Body Surface Area Calculator
Body Surface Area (BSA) is an estimate of the total surface area of the human body and is commonly expressed in square meters (m²). Unlike body weight or Body Mass Index (BMI), BSA combines height and weight to produce a value that can be used as a general representation of body size. BSA is particularly useful in clinical and physiological calculations because some measurements and medical formulas are better expressed relative to body surface area than to body weight alone.
One of the most widely used methods for estimating BSA is the Mosteller formula. It uses height in centimeters and body weight in kilograms and produces a simple estimate of body surface area. Other formulas, including the Du Bois and Du Bois equation, have also been used in medicine and research. Because these equations were developed using different populations and mathematical approaches, their results can differ slightly. The Mosteller equation is popular because it is straightforward to calculate and is practical for routine clinical use.
BSA has been used in several areas of medicine and physiology. It may be incorporated into calculations involving cardiac index, renal function, certain laboratory measurements, and some medication-dosing protocols. BSA is also useful when comparing physiological measurements between individuals of different body sizes. However, BSA is only an estimated measure and does not directly measure the actual surface area of the skin.
BSA should also be distinguished from BMI. BMI is calculated from weight and height and is mainly used as a screening measure of body size, whereas BSA is an estimate of physical surface area. Neither measurement directly describes body composition, muscle mass, or the distribution of body fat. For this reason, BSA should be interpreted according to the purpose for which it is being used rather than as a standalone measure of health.
How it works
This calculator uses your height and weight to estimate body surface area with the Mosteller formula. The calculation first multiplies height in centimeters by weight in kilograms, divides the result by 3600, and then takes the square root.
Mosteller Formula
The Mosteller equation is commonly used because it provides a relatively simple way to estimate BSA without requiring additional body measurements. For example, a person who is 170 cm tall and weighs 70 kg would have an estimated BSA of approximately 1.82 m².
Height: 170 cm
Weight: 70 kg
BSA = √[(170 × 70) ÷ 3600]
BSA ≈ 1.82 m²
Why Body Surface Area Is Used
BSA can be useful when a physiological or clinical measurement needs to account for differences in body size. In some medical settings, certain treatments or calculations may use BSA as one of several factors. The appropriate method depends on the specific clinical situation, and healthcare professionals may use additional measurements, laboratory results, organ function, age, and other patient-specific information.
BSA and Body Size
Body surface area generally increases as height and weight increase. However, the relationship is not linear because the Mosteller equation uses the square root of the product of height and weight. This means that two people with the same weight can have different estimated BSA values if their heights differ, and two people with the same height can also have different BSA values when their weights differ.
Understanding the Result
The result is reported in square meters (m²). A value around 1.7–1.9 m² is common among many average-sized adults, but there is no single BSA value that should be considered universally normal. BSA naturally varies with body size, age, sex, and other physical characteristics. The result should therefore be interpreted according to the context in which BSA is being used.
Important Considerations
BSA is an estimate rather than a direct measurement. Different equations may produce slightly different results, particularly for people whose height or weight differs substantially from the populations used to develop the equations. In addition, BSA does not indicate whether a person's body weight is healthy and should not be used as a replacement for BMI, body-composition measurements, or a clinical assessment.
Medical Disclaimer
This calculator is provided for informational and educational purposes only. Results are estimates and should not be considered medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional for medical decisions.