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Body Surface Area Calculator

Calculate your body surface area (BSA) in square metres from your height and weight. This calculator uses the widely used Mosteller formula to estimate body surface area.

1

Your weight

lb
Enter your current body weight. Imperial values are converted to kilograms for the Mosteller formula.
2

Your height

in
Enter your total height in inches. For example, 5 ft 9 in equals 69 inches.
3

Measurement units

Switch to metric if you prefer to enter your weight in kilograms and height in centimetres.

Your estimated body surface area:

0.00 m²

Your result is an estimate calculated from your height and weight using the Mosteller formula.

Your body surface area

0.00 m²
body surface area
0.00 m²
reference: 1.73 m²
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This result is an informational estimate for educational purposes only and is not medical advice. Body surface area is estimated mathematically from height and weight. It should not be used by itself to determine medication doses or other medical decisions.
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How does the Body Surface Area Calculator work?

The Body Surface Area Calculator estimates your body surface area in square metres using your height and weight. It uses the Mosteller formula, a simple and widely used BSA estimation method. Unlike calculators that require age, sex or body-fat measurements, the Mosteller equation uses only height and body weight.

Term What does it mean? In the calculation Why does it matter?
Body weight Your body mass entered in pounds or kilograms. kg One of the two direct inputs used by the Mosteller formula.
Height Your standing height entered in inches or centimetres. cm Height and weight together determine the estimated body surface area.
Body surface area An estimate of the external surface area of the body. m² BSA is used in various body-size-normalized physiological and clinical calculations.
Mosteller formula A simplified square-root equation for estimating body surface area. √[(cm × kg) ÷ 3600] This is the published formula used by this calculator.
3600 constant The scaling constant used in the Mosteller equation. 3600 It scales the height-weight product within the formula before taking the square root.
1.73 m² A commonly used reference body surface area value in adults. reference It can provide context, but it is not an individual health target or diagnostic threshold.

1. Convert the measurements

If you use imperial units, the calculator converts pounds to kilograms and inches to centimetres. This ensures that the underlying calculation always uses the metric units specified by the Mosteller formula.

2. Apply the Mosteller formula

Height in centimetres is multiplied by weight in kilograms, then divided by 3600. The square root of that result gives the estimated body surface area in square metres.

3. Interpret the result

The final value is a mathematical estimate of body surface area based on your body size. BSA can be useful in certain clinical and physiological calculations, but the number itself is not a health rating or diagnosis.

Mosteller body surface area formula:
BSA (m²) = √[(height (cm) × weight (kg)) ÷ 3600]

Example:
For a person who is 175 cm tall and weighs 70 kg:
BSA = √[(175 × 70) ÷ 3600]
BSA = √3.4028
BSA ≈ 1.84 m²

Imperial measurements:
The calculator converts pounds and inches to kilograms and centimetres before applying the same Mosteller formula.

Body surface area is an estimate because the body's actual external surface is not directly measured. The Mosteller formula was published by R. D. Mosteller in 1987 as a simplified body-surface-area calculation. BSA is used in various clinical and physiological applications, but medication dosing or other medical decisions should always follow the relevant professional protocol and guidance from a healthcare professional.

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Fitness Calculators
Body Surface Area Calculator

Body Surface Area Calculator estimates your body surface area in square metres using your height and weight. The calculator uses the widely used Mosteller formula, which combines height in centimetres and weight in kilograms. BSA provides a useful body-size measurement that is used in certain physiological and clinical calculations. The result is an estimate for informational purposes and is not medical advice.

Medical Disclaimer: The calculator results and information provided in this article are for educational and informational purposes only and do not constitute medical, health, or professional advice. Always consult with a qualified healthcare provider before making any decisions related to your health, diet, or fitness goals. Individual results may vary, and this tool should not be used to diagnose or treat any medical condition.

What is body surface area?

Body surface area, or BSA, is an estimate of the external surface area of the human body. It is usually expressed in square metres and can be estimated from measurements such as height and body weight. Unlike BMI, BSA is intended to describe overall body size rather than categorize body weight.

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How is body surface area calculated?

The Mosteller formula calculates BSA from height and body weight. Height in centimetres is multiplied by weight in kilograms, divided by 3600, and the square root of the result is taken. The final value is expressed in square metres.

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What is the Mosteller formula for BSA?

The Mosteller formula is a simplified body surface area equation published by R. D. Mosteller in 1987. Its formula is BSA = √[(height in cm × weight in kg) ÷ 3600]. Its simplicity makes it practical for calculating BSA without the more complicated exponent-based equations used by some other methods.

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What is the average body surface area?

A BSA of approximately 1.73 m² is commonly used as a reference adult body surface area in certain physiological and clinical calculations. It is not an ideal value that everyone should reach because body surface area naturally varies with height and weight. A person's calculated BSA should therefore be interpreted in the context of their body size.

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What is body surface area used for?

BSA is used in several medical and physiological applications, including certain calculations that normalize measurements for body size. Some medication protocols also use doses expressed per square metre, although the appropriate formula and dosing rules depend on the specific clinical protocol. A BSA calculator should therefore not be used by itself to determine medication doses.

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Is body surface area useful for fitness?

BSA can provide another way of describing overall body size alongside measurements such as body weight, BMI and waist circumference. It can be useful when comparing body-size-related measurements between people of different heights and weights. However, BSA does not directly measure body fat, muscle mass, fitness or athletic performance.

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