Health

Body Surface Area (BSA) Calculator

Calculate body surface area (BSA) in m² instantly from height and weight using both the Mosteller and Du Bois formulas.

Body Surface Area (BSA) Calculator

Height (cm)

Weight (kg)

Method

How this calculator works

Mosteller: BSA (m²) = √(height_cm × weight_kg / 3600). Du Bois: BSA = 0.007184 × height_cm^0.725 × weight_kg^0.425.

Measure the patient's height in centimeters and current weight in kilograms.
Multiply height by weight, then divide by 3600.
Take the square root of that value to obtain the Mosteller BSA in m².
Compare with the Du Bois estimate, which uses fixed exponents on height and weight.

Examples

Worked examples

Real numbers, end-to-end results.

Height 180 cm, weight 75 kg (Mosteller)

= 1.94 m²

√(180 × 75 / 3600) = √3.75 ≈ 1.94 m².

Height 160 cm, weight 55 kg (Mosteller)

= 1.56 m²

√(160 × 55 / 3600) = √2.444 ≈ 1.56 m².

Height 180 cm, weight 75 kg (Du Bois)

= 1.94 m²

0.007184 × 180^0.725 × 75^0.425 ≈ 1.94 m².

Use cases

When to use it

Calculating body-surface-based chemotherapy and drug doses.
Determining cardiac index and other indexed cardiovascular measures.
Estimating basal metabolic rate and fluid or nutrition requirements.
Standardizing physiological measurements across patients of different sizes.

Disclaimer: This calculator provides estimates for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider for decisions affecting your health. Results depend on the accuracy of inputs provided.

FAQ

Frequently asked questions

What is body surface area (BSA)?

Body surface area is the measured or calculated total surface area of the human body, expressed in square meters (m²). It is widely used in medicine—especially for chemotherapy dosing, cardiac index, and estimating metabolic needs—because it correlates better with many physiological processes than body weight alone.

Which BSA formula should I use?

The Mosteller formula is the most popular in clinical practice because it is simple and accurate: BSA = √(height × weight / 3600). The Du Bois formula is the historical standard and still appears in many references. Both give very similar results for most adults, so this calculator shows you both.

What units does this calculator use?

Enter height in centimeters (cm) and weight in kilograms (kg). The result is returned in square meters (m²), the standard unit for BSA in medicine worldwide.

What is a normal BSA value?

The average adult BSA is about 1.7 m². Men typically average around 1.9 m² and women around 1.6 m². Values vary widely with height and build, so there is no single 'correct' number—BSA is simply a scaling factor, not a health score.

Why is BSA used for drug dosing?

Many drugs, particularly chemotherapy agents, are cleared by the body at a rate that tracks more closely with surface area than with weight. Dosing per m² helps deliver a consistent, effective, and safer amount across patients of different sizes.