BSA Calculator (Body Surface Area)

Calculate your Body Surface Area (BSA) by entering your weight, height, and sex. Results are computed using both the Du Bois and Mosteller formulas, returning your BSA in m² and ft² — helping you compare against average values for newborns, children, and adults.

Disclaimer: This tool is for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making any health-related decisions.

Sex *

cm
ft

Only used when Height Unit is set to Feet & Inches

in

Only used when Height Unit is set to Feet & Inches

Results

BSA – Mosteller (m²)

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BSA – Mosteller (ft²)

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BSA – Du Bois (m²)

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BSA – Du Bois (ft²)

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Reference Category

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Frequently Asked Questions

What is Body Surface Area (BSA)?

Body Surface Area (BSA) is the total surface area of the human body measured in square meters (m²) or square feet (ft²). It is widely used in clinical settings — especially for calculating drug dosages, burn area assessments, and renal function estimates — because it is a better indicator of metabolic mass than body weight alone.

What is the difference between the Du Bois and Mosteller formulas?

The Du Bois formula (1916) is one of the oldest and most referenced: BSA = 0.007184 × W^0.425 × H^0.725. The Mosteller formula (1987) is simpler and widely used in clinical practice: BSA = √(H × W / 3600). Both produce very similar results for adults of average build, but may differ slightly for very large or very small individuals.

Why is BSA preferred over body weight for drug dosing?

BSA is preferred because it correlates more closely with several physiological parameters, including cardiac output, renal clearance, and metabolic rate. Many chemotherapy drugs and some cardiac medications are dosed per m² of BSA to ensure consistent therapeutic effects across patients of different sizes.

What is the average BSA for an adult male and female?

The average BSA for an adult male is approximately 1.9 m² (20.45 ft²), and for an adult female it is approximately 1.6 m² (17.22 ft²). BSA varies considerably with age: a newborn averages about 0.25 m², a 2-year-old about 0.5 m², and a 10-year-old about 1.14 m².

Can I use this BSA calculator for children?

Yes, the calculator works for all age groups including children and infants, as long as accurate weight and height measurements are entered. However, always consult a healthcare professional when using BSA-based dosing for pediatric patients, as clinical judgment is essential.

How do I convert between BSA in m² and ft²?

To convert BSA from square meters to square feet, multiply by 10.7639. For example, a BSA of 1.9 m² equals approximately 20.45 ft². This calculator displays results in both units automatically.

Is BSA the same as BMI?

No. BMI (Body Mass Index) is calculated from weight divided by height squared and gives a ratio used to classify underweight, normal, overweight, or obese categories. BSA measures the actual physical surface area of the body and is used primarily for clinical and pharmacological purposes, not weight classification.

How accurate are BSA formulas?

All BSA formulas are estimates since direct measurement of body surface area is complex and impractical in clinical settings. The Mosteller and Du Bois formulas are validated for adults of typical proportions and are widely accepted in medical practice. They may be less accurate at the extremes of body size, such as morbidly obese individuals or very premature infants.