Mosteller BSA Calculator
Calculate body surface area (BSA) using the Mosteller formula. Choose your unit system, enter height and weight, then click calculate.
What Is BSA and Why Does It Matter?
Body Surface Area (BSA) is an estimate of the total surface area of a human body. It is commonly used in medicine to help standardize clinical decisions, especially in areas like chemotherapy dosing, burn assessment, fluid calculations, and kidney function interpretation. Compared with body weight alone, BSA can better account for differences in body size and proportions.
The Mosteller equation is one of the most widely used BSA formulas because it is simple, fast, and reasonably accurate for many practical settings.
The Mosteller Formula
The Mosteller formula is:
BSA (m²) = √[(Height (cm) × Weight (kg)) / 3600]
This approach became popular because it is straightforward and easy to calculate manually or digitally while still aligning well with more complex formulas in day-to-day clinical use.
Quick Example
If someone is 170 cm tall and weighs 70 kg:
- 170 × 70 = 11,900
- 11,900 / 3600 = 3.3056
- √3.3056 ≈ 1.82
Estimated BSA = 1.82 m².
How to Use This BSA Calculator
- Select your preferred unit system (metric or imperial).
- Enter your height and weight values.
- Click Calculate BSA.
- Read your result in square meters (m²), including converted metric values when needed.
For imperial entries, this calculator converts feet/inches to centimeters and pounds to kilograms before applying the Mosteller equation.
Mosteller vs Other BSA Equations
There are multiple body surface area formulas in use. The “best” formula depends on the context, patient population, and institutional protocol.
| Formula | Complexity | Common Use |
|---|---|---|
| Mosteller | Low | General clinical and educational use |
| Du Bois & Du Bois | Moderate | Historical reference, research comparisons |
| Haycock | Moderate | Pediatrics and specialized settings |
| Gehan & George / Boyd | Higher | Research and detailed modeling |
Clinical Context and Practical Caution
BSA can support clinical decisions, but it is not a standalone diagnosis tool. Medication dosing and treatment planning should always be reviewed by licensed professionals, along with:
- Age and organ function
- Comorbidities and disease state
- Lab values and treatment response
- Institutional and specialty-specific guidelines
Typical Adult BSA Ranges
While there is broad variation, many adults fall roughly within the 1.5 to 2.3 m² range. Taller and heavier individuals may exceed this range, while smaller adults and many children are below it.
A “normal” value depends on body size, age, and clinical context. Always interpret BSA alongside other measurements.
Frequently Asked Questions
Is Mosteller accurate enough for medical work?
In many routine settings, yes. Mosteller is widely accepted for practical use due to simplicity and reasonable agreement with alternative formulas.
Can I use imperial values directly?
Yes. This calculator converts feet/inches and pounds into centimeters and kilograms automatically before applying the equation.
Why not just use BMI?
BMI and BSA serve different purposes. BMI estimates body mass relative to height, while BSA estimates skin surface area and is often used in medication dosing and physiologic scaling.
Does this work for children?
The Mosteller formula is commonly used in pediatric contexts, but pediatric care decisions require clinician oversight, especially for dosing.
Bottom Line
If you need a fast and practical body surface area estimate, the Mosteller equation is a strong default. Use this calculator for quick results, but always rely on qualified healthcare professionals for clinical interpretation and treatment decisions.