📐 Pharmacology Tool

Body Surface Area (BSA) Calculator

Calculate BSA using all four major formulas: Mosteller, DuBois & DuBois, Haycock, and Boyd. Used for chemotherapy dosing, cardiac output, and burn estimation.

Height

Height Unit

Weight

Weight Unit

Formulas Used

Mosteller: BSA = √(H × W / 3600)
DuBois: BSA = 0.007184 × H⁰·⁷²⁵ × W⁰·⁴²⁵
Haycock: BSA = 0.024265 × H⁰·³³⁶⁴ × W⁰·⁵³⁷⁸
Boyd: BSA = 0.0003207 × H⁰·³ × W⁰·⁷²⁸⁵ ⁻ ⁰·⁰¹⁸⁸ × log(W)

📋 Clinical Uses of BSA

🧪 Chemotherapy

Most chemo drugs are dosed in mg/m². BSA ensures consistent drug exposure regardless of body size. Mosteller or DuBois are most common in oncology.

❤️ Cardiac Output

Cardiac index = Cardiac Output ÷ BSA. Normalizes CO for comparison across body sizes (normal CI: 2.5–4.0 L/min/m²).

🔥 Burn Estimation

The Rule of Nines estimates % TBSA burned. BSA provides context for fluid resuscitation using the Parkland formula.

💊 Renal Dosing

GFR can be normalized to 1.73 m² (average adult BSA). Adjusts drug dosing for patients significantly above or below average BSA.

Frequently Asked Questions

Which BSA formula should I use?

For adults: Mosteller is the easiest to remember and the most widely used in clinical practice today. DuBois was the original and is still used in many legacy protocols. For children and extremely high or low body weight patients: Haycock is preferred, as it was validated specifically for pediatric patients. Boyd performs similarly to Haycock for children. When in doubt, follow your institution's oncology or pharmacy protocol, which will specify the required formula.

What is a normal adult BSA?

The average adult BSA is 1.7–1.8 m². The "standard" BSA used in some pharmacokinetic studies is 1.73 m². Adult females average approximately 1.6 m² and adult males average approximately 1.9 m². Children have proportionally smaller BSA — a 10-year-old averages around 1.14 m².

How is BSA different from BMI?

BMI (kg/m²) estimates body fatness and obesity risk. BSA (m²) measures the total external surface area of the body, which correlates better with metabolic rate and cardiac output than weight alone. For drug dosing purposes, BSA is more accurate than weight alone because it accounts for height, making it less influenced by excess body fat.