Body Surface Area (BSA) Calculator

What is body surface area (BSA)?

Body Surface Area (BSA) estimates the total external surface of the human body, expressed in square meters (m²). In healthcare, BSA is widely used to scale medication doses, evaluate metabolic demand, and index physiological measures such as cardiac output. Because it accounts for both height and weight, BSA can be more informative than weight alone for certain clinical decisions.

BSA is a practical bridge between body size and dosing decisions. It’s not a diagnosis—just one piece of the clinical picture.

Common BSA formulas used in practice

• Du Bois: 0.007184 × height(cm)^0.725 × weight(kg)^0.425
• Mosteller: √(height(cm) × weight(kg) / 3600)
• Haycock: 0.024265 × height(cm)^0.3964 × weight(kg)^0.5378
• Gehan & George: 0.0235 × height(cm)^0.42246 × weight(kg)^0.51456
• Boyd: 0.0003207 × height(cm)^0.3 × weight(kg)^(0.7285 − 0.0188 × log10(weight(kg)))

Why multiple formulas?

Different formulas were derived from different study populations and methods. While results are usually similar, small variations exist. This tool calculates all five formulas and gives you an overall average to keep decisions balanced and consistent across contexts.

For students and professionals

Students can explore how anthropometric equations work, compare outputs, and understand unit conversions. Clinicians and pharmacists can use the quick outputs for education and planning, then apply clinical judgment and institutional protocols in practice.

Frequently asked questions