We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What is Body Surface Area?

Mary McMahon
Updated Mar 03, 2024
Our promise to you
The Health Board is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At The Health Board, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject-matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

Body surface area (BSA) is an estimation of a person's total surface area, based on a calculation involving weight and height. A simple calculation multiplies the weight by the height, divides by 3,131 if the measurements are in pounds and inches, or by 3,600 if in meters and kilograms, and then takes the square root of the remaining number. This formula is known as the Mosteller formula and it is popular with medical practitioners for its ease of use and accurate results.

Looking at body surface area can provide useful information about deposits of fat on a patient's body, and it is sometimes compared to the body mass index (BMI). Some people feel that body surface area creates a more accurate picture, as people who are unusually heavy for their height will have a correspondingly high surface area, illustrating the deposition of fat on their frames. The calculation is only an estimate, and it is important to consider factors like a patient who exercises a lot and may be heavier as a result of being well-muscled, as muscle tissue is very heavy.

People use the body surface area to determine the dosage of some kinds of medication. Drugs like chemotherapy must be calculated very carefully to ensure the appropriateness of the dosage for a patient. Intravenous fluids are also commonly dosed on the basis of body surface area. Care providers who regularly determine medication dosages may carry a small calculator to make it easier to accurately compute doses for their patients.

This calculation can also be used for other situations. Care providers interested in determining a patient's renal clearance to assess the health of the kidneys can use body surface area to get a clear idea of how much the kidneys are filtering in a given time period. It can also be used in the computation of the cardiac index, comparing cardiac output to a patient's size. This should fall within a stable range, showing that a patient has a healthy heart. If it is unusually low, there may be a problem with the patient's heart function.

Some factors can change body surface area and make a patient's actual surface area differ from the number determined by calculating. People who have lost a lot of weight rapidly, for example, may have large skin folds that increase their surface area but aren't revealed in a simple formula involving their weight and height.

The Health Board is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Mary McMahon
By Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a The Health Board researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Discussion Comments
By lluviaporos — On Oct 28, 2014

@clintflint - I'm sure it makes a difference when they need to measure rashes and burns and in calculating topical medicines, if not other kinds of medicine. The total surface area of a body probably helps to estimate the total amount of blood vessels and so forth for example.

Hopefully any doctor who is working with a patient where this is a crucial number to know will use a more complex equation to figure it out as there are a number of factors that can make a difference. But if they just want a rough estimate I'm sure the standard formula is fine.

By clintflint — On Oct 28, 2014

@bythewell - I guess that's why I tend to dislike living anywhere the summers get too hot, as I'm overweight and I seem to have more trouble cooling down than skinnier people do. I'm sure there are other factors as well.

I've never heard of body surface area as being a way that people calculate medicine dosage. It sounds like the equation is very similar to calculating BMI, so it would be subject to the same limitations.

By bythewell — On Oct 28, 2014

I remember learning in biology about this in relation to people who evolved in different areas. The example they used was that people from hot countries tended to be taller and skinnier than people from cold countries (assuming that their ancestors had lived in the same climate) because taller and skinnier people had more total body surface area proportionate to their weight.

The less surface area you have, the easier it is to conserve heat, because there is less space for it to evaporate. On the other hand, if you live in a very hot place you will want a lot of surface area so that you can cool down as efficiently as possible.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a...

Learn more
The Health Board, in your inbox

Our latest articles, guides, and more, delivered daily.

The Health Board, in your inbox

Our latest articles, guides, and more, delivered daily.