Body & Fitness

Body Surface Area (BSA) Calculator

Calculate body surface area (BSA) using the Mosteller formula.

By Calculator Suite Pro Editorial Team | Last updated March 18, 2026

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Weight (kg)Height (cm)

BSA

1.909 m^2

Formula

Mosteller

Note

Reference

Confirm clinical use with professionals.

Direct answer

Body Surface Area (BSA) Calculator gives an instant result from your inputs. Body Surface Area (BSA) estimates the external surface area of the human body. It is commonly used in medical contexts such as medication dosing references and clinical assessments. Formula snapshot: Mosteller formula: BSA = sqrt((heightCm x weightKg) / 3600). Example: Height: 175cm, Weight: 75kg -> BSA shown in m^2.

About this calculator

Body Surface Area (BSA) estimates the external surface area of the human body. It is commonly used in medical contexts such as medication dosing references and clinical assessments.

This calculator uses the Mosteller formula, which is widely used due to simplicity and reasonable accuracy for many adults.

BSA is a reference estimate and should not replace professional medical guidance for dosing or clinical decisions.

How it works

A quick explanation of the logic behind the results, so you can trust what you see.

Mosteller formula: BSA = sqrt((heightCm x weightKg) / 3600).
Height and weight are combined into a scale factor and then square-rooted.
The output unit is square meters (m^2).
Different BSA formulas exist; Mosteller is popular because it is simple and practical.

Formula used

These are the core formulas and logic rules used by this calculator.

Mosteller formula: BSA = sqrt((heightCm x weightKg) / 3600).
Different BSA formulas exist; Mosteller is popular because it is simple and practical.

Common use cases

Below are common real-world scenarios where this calculator is useful.

Clinical reference calculations (with professional guidance)
Education and learning BSA formulas
Quick BSA estimate from height and weight
Comparing changes as weight changes
General health knowledge
Research and academic exercises
Medical dosing discussions (reference only)
Fitness/health reporting context (reference only)

How to use

Enter your weight (kg).
Enter your height (cm).
Calculate to see BSA in square meters (m^2).
Use the value as a reference estimate.
If the value is used medically, confirm with a clinician.

Common mistakes to avoid

These are the issues that most often cause confusing results.

Entering height in meters instead of centimeters.
Entering weight in pounds instead of kilograms.
Assuming BSA is a precise measurement (it is an estimate).
Using BSA directly for dosing without professional oversight.
Comparing BSA across formulas and expecting identical values.

Tips and notes

Double-check units: kg and cm are required for this calculator.
If you only have imperial units, convert them first for best accuracy.
Use the result as a reference, not a medical instruction.
For general body composition, use BMI, body fat percentage, and waist ratios.

Glossary

Quick definitions for common terms used in this calculator.

BSA

Body Surface Area: an estimate of the body's external surface area.

Mosteller formula

A common BSA formula: sqrt((heightCm x weightKg) / 3600).

Examples

Example

Input: Height: 175cm, Weight: 75kg

Output: BSA shown in m^2

Example

Input: Height: 165cm, Weight: 60kg

Output: BSA shown in m^2

Weight change

Input: Same height, higher weight

Output: BSA increases

FAQ

What is BSA used for?

BSA is often used as a reference in clinical settings, including dosing guidelines and assessments.

Which formula does this use?

This calculator uses the Mosteller formula.

Is BSA the same as BMI?

No. BMI is weight-to-height ratio for screening. BSA estimates external surface area.

Is this accurate for everyone?

It is a practical estimate, but individuals vary. Different formulas can produce slightly different values.

Can I use this for children?

BSA can be used in pediatrics, but dosing and interpretation should be done by clinicians.

Do you store my inputs?

Most calculations run in your browser. No signup is required.

Is this calculator free to use?

Yes. This calculator is free to use without signup.

Can I use this calculator on mobile?

Yes. The calculator is mobile-friendly and works on desktop as well.

Last updated and references

Last updated: March 18, 2026

Reviewed by Calculator Suite Pro Editorial Team.

For sensitive health and finance topics, review official sources in addition to calculator outputs.

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