About Body Surface Area Calculator

Calculates body surface area using four established medical formulas: DuBois & DuBois (1916, the clinical standard), Mosteller (1987, simplified square-root formula), Haycock (1978, more accurate for children), and Boyd (1935, better for obese patients). Displays all four results simultaneously so you can compare. Used in clinical contexts for drug dosing, burn assessment, and renal function calculations.

• DuBois formula: 0.007184 × W⁰·⁴²⁵ × H⁰·⁷²⁵ — the standard used in most clinical settings since 1916
• Mosteller formula: √(H × W ÷ 3600) — simpler to compute, widely used when a quick estimate is sufficient
• Haycock formula: 0.024265 × W⁰·⁵³⁷⁸ × H⁰·³⁹⁶⁴ — developed for pediatric patients, more accurate at lower body weights
• Boyd formula: uses a complex logarithmic calculation—more reliable for patients with obesity or unusual body proportions
• Size categories: Small (<1.3 m²), Average (1.3–1.7 m²), Large (1.7–2.1 m²), Very Large (>2.1 m²)

Frequently Asked Questions

Why are there four different formulas?

Each was developed for a different population or use case. DuBois is the clinical default but was derived from a small sample. Haycock is better for children. Boyd handles obesity better. Mosteller trades some accuracy for simplicity. In practice, the results rarely diverge by more than 5–10% for typical adults.

What is BSA used for in medicine?

Primarily chemotherapy dosing—most chemo drugs are dosed per m² of body surface area rather than per kg, because BSA correlates better with metabolic rate and organ size. Also used for calculating glomerular filtration rate (kidney function) and assessing burn severity.