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Professional BSA Calculator

Calculate Body Surface Area using five authoritative formulas (DuBois, Mosteller, Haycock, Gehan & George, Boyd). Metric & imperial.

Mosteller BSA (Recommended)

1.80 m²

Also known as the standard medical BSA

All Formula Results (m²)

DuBois & DuBois 1.81
Mosteller 1.80
Haycock 1.79
Gehan & George 1.81
Boyd 1.79

Values may vary slightly between formulas.

📋 Clinical Applications

  • Chemotherapy Dosing: Many anticancer drugs are dosed based on BSA (mg/m²).
  • Cardiac Index: Cardiac output normalized to BSA.
  • Renal Function: GFR is often corrected for BSA.
  • Burn Assessment: Rule of Nines estimates burn extent relative to BSA.

🧪 Formula Overview

DuBoisBSA = 0.007184 × W0.425 × H0.725
MostellerBSA = √[(H × W)/3600]
HaycockBSA = 0.024265 × W0.5378 × H0.3964
Gehan & GeorgeBSA = 0.0235 × W0.51456 × H0.42246
BoydBSA = 0.0003207 × W0.7285‑0.0188 log(W) × H0.3

W = weight (kg), H = height (cm).

Body Surface Area (BSA): The Gold Standard for Metabolic Mass

Body Surface Area (BSA) is a critical biometric used extensively in clinical medicine. Unlike body weight alone, BSA correlates more strongly with metabolic rate, blood volume, and organ size. This Professional BSA Calculator provides results from five validated formulas, allowing clinicians, researchers, and informed patients to select the most appropriate value for their specific application.

Why BSA Matters in Medicine

  • Chemotherapy: Most chemotherapeutic agents have a narrow therapeutic index. Dosing based on BSA (mg/m²) minimizes toxicity while maintaining efficacy.
  • Cardiology: Cardiac output is often indexed to BSA (cardiac index) to compare patients of different sizes.
  • Nephrology: Glomerular filtration rate (GFR) is routinely normalized to a standard BSA of 1.73 m².
  • Burn Care: The "Rule of Nines" and Lund‑Browder charts use BSA to estimate fluid resuscitation needs.

💡 Which Formula Should I Use?

Mosteller is the simplest and most commonly used in clinical practice. DuBois is the historical gold standard. Haycock is often preferred for pediatric patients. Gehan & George and Boyd offer alternative validations. The differences are usually clinically insignificant for average‑sized adults.

BSA and Drug Dosing: A Deeper Look

The rationale for BSA‑based dosing is that many physiological parameters (e.g., cardiac output, liver blood flow, glomerular filtration) are proportional to BSA. This normalizes drug exposure across patients of varying body sizes. However, for obese patients, alternative dosing strategies (e.g., using ideal body weight) may be considered to avoid overdosing.

Frequently Asked Questions

What is the average BSA for an adult?

Average BSA is approximately 1.7 m² for adult females and 1.9 m² for adult males. "Standard" BSA is often taken as 1.73 m², which is the average of a 70 kg, 170 cm adult.

Can I use this calculator for children?

Yes. The formulas are valid for all ages. The Haycock formula was specifically validated in infants and children.

How does BSA relate to BMI?

BSA and BMI are related but not interchangeable. BMI is weight/height², while BSA is weight^0.425 × height^0.725 (DuBois). BSA increases more slowly with weight than BMI does.

Why do different formulas give slightly different results?

Each formula was derived from different populations and statistical methods. For most adults, the variation is within 1‑2%. Clinicians often standardize on one formula within an institution.

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