BSA Calculator - Body Surface Area for Drug Dosage
Calculate Body Surface Area (BSA) using Mosteller, DuBois, Haycock, and Gehan-George formulas. Medical calculator for drug dosing, burn assessment, cardiac index, and chemotherapy dosing. Essential for clinical practice and pharmacological calculations.
BSA (Du Bois) Formula
BSA = 0.007184 × W^0.425 × H^0.725Variables:
- BSABody Surface Area in m²Body Surface Area in m²(e.g.: 1.73 m²)
- WBody weight in kgBody weight in kg(e.g.: 70 kg)
- HHeight in cmHeight in cm(e.g.: 170 cm)
How to Calculate BSA
- 1
Enter Body Weight
Enter weight in kilograms.
- 2
Enter Height
Enter height in centimeters.
- 3
Select Formula
Choose formula: Du Bois, Mosteller, or Haycock.
- 4
View Result
BSA in m² is displayed.
Examples
Standard Adult BSA
Problem:
Calculate BSA: weight 70 kg, height 170 cm.
Solution:
- 1.Mosteller formula: BSA = √(H × W / 3600)
- 2.BSA = √(170 × 70 / 3600)
- 3.BSA = √(11900 / 3600)
- 4.BSA = √3.306
Result:1.82 m²
Average adult BSA is about 1.7–1.9 m².
Child BSA
Problem:
Calculate child BSA: weight 20 kg, height 110 cm.
Solution:
- 1.BSA = √(110 × 20 / 3600)
- 2.BSA = √(2200 / 3600)
- 3.BSA = √0.611
Result:0.78 m²
Child BSA is smaller; drug doses are adjusted proportionally.
Frequently Asked Questions
When is BSA used?
BSA is mainly used in oncology to determine chemotherapy doses. It is also used for certain antibiotics, burn treatment, and kidney function parameters (GFR adjusted to BSA).
Why not use body weight alone?
BSA better reflects body metabolism than weight alone. A tall thin person and a short heavy person with the same weight have different BSA, affecting drug distribution.
Which formula is most accurate?
Du Bois (1916) is the most traditional. Mosteller (1987) is simpler. For children, Haycock is recommended. Differences are small within the normal range.
What is normal BSA?
Adult BSA: men ~1.9 m², women ~1.6 m² (average). Normal range 1.5–2.2 m². Newborns are about 0.25 m².