What this Body Surface Area Calculator does
This Body Surface Area Calculator estimates a person's body surface area (BSA) in square meters from height and weight. It uses the Mosteller formula, a commonly used equation that combines those two measurements into one estimate. Enter height in centimeters and weight in kilograms to see the result rounded to two decimal places.
BSA is a calculated measure of the body's external surface area. It is used in some clinical contexts as one of several measurements that help describe body size. This estimate is not a direct measurement of skin area, a diagnosis, or a complete assessment of health, fitness, or nutritional status. People with the same height and weight can have different body composition and body shape, which this equation does not represent.
The calculator title is Body Surface Area Calculator, and its description is to estimate BSA in square meters using the Mosteller formula and user supplied height and weight. Its inputs are Height (cm) and Weight (kg). The result label is Estimated Body Surface Area (m²).
How to use the Body Surface Area Calculator
Use recent measurements and check the units before calculating. The accepted height range is 100 to 250 cm, and the accepted weight range is 20 to 300 kg. These limits define what can be entered in this tool. They are not clinical suitability thresholds.
- Measure or enter height in centimeters. If your measurement is in meters, multiply it by 100 to convert to centimeters.
- Enter weight in kilograms. If you have a measurement in another unit, convert it to kilograms before entering it.
- Select calculate to see the estimated BSA in square meters.
- Keep the result rounded to two decimal places when referring to this calculator's displayed estimate.
For example, a person who is 170 cm tall and weighs 70 kg enters 170 for height and 70 for weight. The estimate is the square root of (170 × 70 ÷ 3600), which is approximately 1.82 m². Small differences in the recorded measurements can change the rounded result.
How the Body Surface Area formula works
The calculator applies the Mosteller equation: BSA = √[(height in centimeters × weight in kilograms) ÷ 3600]. In the configuration, the same equation is written as Math.pow((height_cm * weight_kg) / 3600, 0.5), where Math.pow raises the value to the power of one half, equivalent to taking its square root.
The formula combines height and weight, divides their product by 3600, and takes the square root. With the example values, 170 × 70 = 11,900. Dividing 11,900 by 3600 gives approximately 3.3056. The square root is approximately 1.818, so the calculator displays 1.82 m².
Using the specified units matters because the constant in this version of the equation is paired with centimeters and kilograms. Entering inches or pounds as though they were centimeters or kilograms would produce an incorrect estimate. The calculator does not convert units automatically.
Use cases for the Body Surface Area Calculator
This estimate can help someone understand how a height and weight pair is expressed as BSA under a particular equation. It may also be useful for learning how a formula works or checking arithmetic in an educational setting. In healthcare, a clinician may consider BSA alongside other information when interpreting a measurement or planning care.
A calculator result alone cannot determine a person's health needs or establish what treatment is appropriate. Clinical decisions depend on the specific situation, the intended use of the measurement, and other relevant information. If a health professional has given you a specific method or measurement instructions, follow those instructions and ask them how to interpret your result.
Other factors to consider when calculating body surface area
BSA is an estimate from two inputs. It does not account for body composition, age, pregnancy, swelling, fluid changes, or differences in body shape. It also cannot tell whether a person's weight is healthy or whether an activity plan is suitable. Those questions require context beyond this equation.
Results may vary when another BSA equation is used, or when different measurement methods or rounding rules are applied. For comparisons over time, use consistent units and measurement practices. Record the date and source of measurements when that context matters.
- Check that height is entered in centimeters and weight in kilograms.
- Use measurements that are as accurate and current as practical for the intended purpose.
- Remember that the displayed value is rounded to two decimal places.
- Ask a qualified healthcare professional to interpret BSA when it relates to care or treatment.
Frequently asked questions
What does BSA mean?
BSA means body surface area. This calculator estimates it in square meters from height and weight using the Mosteller equation.
Why does the calculator ask for height and weight?
Both measurements are inputs to the formula. Their product is divided by 3600, and the square root of that value gives the estimate in square meters when the specified units are used.
Can I enter height in inches or weight in pounds?
No. This calculator expects height in centimeters and weight in kilograms. Convert measurements to those units before entering them to avoid a unit mismatch.
Is this result a direct measurement or a diagnosis?
No. It is a formula-based estimate, not a direct measurement, diagnosis, or personal treatment recommendation. A healthcare professional can explain whether BSA is relevant to a particular health question.
Why might another calculator show a different result?
Different tools may use another equation, different input units, different source measurements, or different rounding rules. Check the method and units before comparing estimates.