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Body Surface Area (Mosteller) Calculator

Calculates total surface area of human body for drug dosing.

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Body Surface Area

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Overview

The Mosteller formula provides a simplified calculation for Body Surface Area (BSA), which is essential for standardizing physiological parameters and determining precise drug dosages. It relates height and weight through a square root function to estimate the total surface area of the human body in square meters.

Symbols

Variables

BSA = Body Surface Area, H = Height, W = Weight

Body Surface Area
Height
Weight

Apply it well

When To Use

When to use: This formula is used primarily in oncology and critical care to calculate dosages for medications with narrow therapeutic windows. It is applicable for both adults and children, making it a versatile tool in clinical settings compared to more complex alternatives like the Du Bois formula.

Why it matters: Using BSA instead of weight alone prevents under-dosing in tall, thin patients and over-dosing in shorter, heavier patients. It serves as the basis for calculating indices like the Cardiac Index and allows for accurate comparisons of metabolic functions between individuals of different sizes.

Avoid these traps

Common Mistakes

  • Using weight in lbs or height in inches without adjusting formula constants.
  • Forgetting the square root step.

One free problem

Practice Problem

A clinical pharmacist needs to calculate the Body Surface Area (BSA) for an adult male patient who stands 180 cm tall and weighs 80 kg. Using the Mosteller formula, what is the patient's BSA in m²?

Height180 cm
Weight80 kg

Solve for:

Hint: Multiply height by weight, divide by 3600, then find the square root of the result.

The full worked solution stays in the interactive walkthrough.

References

Sources

  1. Mosteller, R. D. (1987). Simplified calculation of body-surface area. New England Journal of Medicine, 317(17), 1098.
  2. Wikipedia: Body surface area (specifically the 'Mosteller formula' section)
  3. Goodman & Gilman's The Pharmacological Basis of Therapeutics
  4. Mosteller, R. D. (1987). Simplified calculation of body-surface area. The New England Journal of Medicine, 317(17), 1098-1098.
  5. Wikipedia: Body surface area
  6. Mosteller RD. Simplified calculation of body-surface area. N Engl J Med. 1987 Oct 22;317(17):1098.
  7. Body surface area (Wikipedia article)
  8. Harrison's Principles of Internal Medicine