Body Surface Area (BSA) Calculator

Body surface area (BSA) is an estimate of the total outer surface of the human body, usually expressed in square metres (m²). According to Wikipedia’s body surface area article, BSA is used as a more refined indicator of body size than weight alone in several medical contexts, including some drug dosing schemes and assessment of cardiac output or metabolic rate.

BSA can help standardise measurements between people of different sizes. For example, kidney filtration is often reported as mL/min per 1.73 m², and some chemotherapy regimens are written as a certain number of milligrams per square metre. The BSA Calculator makes it easy to obtain a consistent BSA estimate from height and weight without manually applying the formula.

The calculator uses your height and weight and applies commonly used BSA equations described in medical literature. Depending on the version, it may show one or more formulas such as:

• Mosteller formula – a widely used and simple equation that takes the square root of (height × weight) divided by 3600.
• DuBois and DuBois formula – a classic equation derived from early body surface measurements.

After you enter your height and weight and click “Calculate BSA”, the script:

• Converts your values to the appropriate units if needed (for example cm and kg).
• Applies the selected BSA formula(s).
• Displays your estimated BSA in m², sometimes side by side if multiple equations are shown.

The results are presented with neutral, educational notes rather than prescribing any particular treatment or dose. The goal is to help you understand how BSA is derived, not to make medical decisions automatically.

Although individual equations differ slightly, most BSA formulas share some common ideas:

• Use of height and weight together – combining these two measurements better reflects body size than either one alone.
• Non-linear relationship – BSA increases with body size but not in a simple one-to-one way; formulas use exponents or square roots to capture this.
• Normalisation – many physiological measurements (like cardiac output or GFR) are sometimes divided by BSA to allow fair comparison between people of different builds.
• Approximation – BSA is always an estimate; direct measurement of body surface is rarely performed in everyday practice.

By showing BSA clearly, the calculator helps you see how changes in weight or height affect size-related calculations in other tools, such as drug dosage or kidney filtration estimates.

For complementary size and composition metrics, you may also want to review your BMI Calculator results or explore how BSA interacts with renal estimates in the eGFR Calculator.

Using the BSA Calculator is quick and straightforward:

• Measure or look up your current height and weight.
• Enter these values into the corresponding fields on the calculator, making sure you select the correct units (for example, centimetres and kilograms).
• Click the “Calculate BSA” button.
• Review the estimated BSA in m² and any notes provided about how the value was obtained.

You can repeat the calculation using older or hypothetical weights to see how BSA changes with body size. This is especially useful when looking at dose examples or following educational cases in textbooks or courses.

When exploring dose-related scenarios, some users also combine the BSA result with the Drug Dosage Calculator as a non-medical way to understand how mg/m² dosing is applied in principle.

Because BSA is closely tied to body size, metabolism and dosing, several tools on labscan.cloud work naturally alongside the BSA Calculator:

• BMI Calculator – helps you understand your weight in relation to height and standard BMI categories.
• Drug Dosage Calculator – an educational, non-medical tool that demonstrates how body size can influence dose calculations.
• Creatinine Clearance Calculator – sometimes uses BSA or weight when estimating kidney filtration for dosing purposes.

Together, these tools offer a clearer view of how body size metrics like BSA are used across different areas of clinical reasoning—always with the understanding that real treatment decisions remain with your healthcare professionals.

Is BSA the same as BMI?
No. BMI is a ratio of weight to height used to classify weight categories, while BSA estimates total body surface area in m². They are related to body size but used for different purposes.

Why do some references use different BSA formulas?
Several equations have been proposed over the years. Differences between them are usually small for most adults. The calculator may show more than one estimate for learning purposes, but your doctor or hospital may prefer a specific one.

Can I use this BSA result to set my own medication dose?
No. Even when drugs are written as mg/m², actual dosing must be decided by a qualified prescriber who knows your full medical history, lab results and other medications.

Does this tool apply to children?
Many BSA formulas can technically be used for children, but paediatric dosing and assessment require child-specific guidelines. Always follow your paediatrician’s advice rather than relying on general online calculators.

By combining the BSA Calculator with other tools on labscan.cloud, you can better understand how body size measurements fit into lab interpretation and dosing logic—while keeping all clinical decisions with your healthcare team.