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Body Surface Area Calculator: BSA Formula Explained

Learn what body surface area means, how BSA is estimated from height and weight, and why different formulas can produce different results.

Body Surface Area (BSA): What It Is and How It Is Calculated

What Is Body Surface Area?

Body surface area, or BSA, is an estimated measurement of the surface area of the human body.

Unlike BMI, which produces a weight-to-height index, BSA estimates an area and is commonly expressed in square meters.

How Is BSA Calculated?

Several formulas can estimate BSA.

One widely used approach is the Mosteller formula:

BSA = √[(Height × Weight) ÷ 3600]

When using this formula, height is expressed in centimeters and weight in kilograms.

Because multiple formulas exist, two BSA calculators may produce slightly different results.

Why Is BSA Used?

BSA has applications in healthcare and medical calculations.

For example, some clinical calculations use BSA as one component when determining or interpreting measurements.

However, BSA should not be confused with BMI or body-fat percentage.

BSA vs BMI

BMI asks:

How does body weight relate to height?

BSA asks:

What is the estimated surface area of the body?

They therefore answer different questions.

How Accurate Is BSA?

BSA is an estimate produced by a mathematical formula. It is not a direct measurement of every square centimeter of skin.

Different formulas also make different assumptions.

Use Our BSA Calculator

Enter height and weight into our Body Surface Area Calculator to obtain an estimated BSA.

For clinical applications, always follow the calculation method and guidance specified by the relevant healthcare professional or medical protocol.

Related BMI information

You can also use Open the BMI calculator and Read more helpful articles as part of your workflow.

Practical tips for better results

Before using Body Surface Area (BSA): What It Is and How It Is Calculated, check the original file or information carefully and decide what result you need. A clear starting point makes the process easier to manage and helps you avoid unnecessary changes. If you are working with an online utility, review the available options before processing your file so you can choose settings that match the task.

For regular workflows, keep your files organized and compare the result with the original after processing. This is particularly useful when quality, formatting, compatibility, or file size matters. If the first result is not ideal, adjust the available settings and try again rather than changing several things at once. The goal of a body surface area workflow is to save time while keeping the final result accurate and usable.