Body Surface Area Calculator Formula

Understand the math behind the body surface area calculator. Each variable explained with a worked example.

Use the Body Surface Area Calculator

Formulas Used

Body Surface Area

bsa_m2 = sqrt(weight_kg * height_cm / 3600)

Body Surface Area

bsa_ft2 = sqrt(weight_kg * height_cm / 3600) * 10.764

Variables

VariableDescriptionDefault
weight_lbsBody Weight(lbs)180
height_inchesHeight(inches)70
weight_kgDerived value= weight_lbs * 0.453592calculated
height_cmDerived value= height_inches * 2.54calculated

How It Works

Mosteller Formula for Body Surface Area

BSA (m2) = sqrt(Weight(kg) x Height(cm) / 3600)

Body surface area is used in medicine for:

  • Chemotherapy dosing
  • Drug dosing calculations
  • Burn assessment
  • Cardiac index calculations

    • Average BSA

    The average adult male BSA is approximately 1.9 m2.

    Worked Example

    A 180 lb, 70-inch tall male.

    weight_lbs = 180height_inches = 70
    1. 01Weight = 81.6 kg, Height = 177.8 cm
    2. 02BSA = sqrt(81.6 x 177.8 / 3600)
    3. 03= sqrt(14,508.48 / 3600)
    4. 04= sqrt(4.030) = 2.01 m2

    Ready to run the numbers?

    Open Body Surface Area Calculator