BMI and Body Surface Area (BSA) calculator

BMI and BSA Calculator

Body Mass Index (BMI) is a widely used measure of body fat based on height and weight. It is calculated by dividing body weight in kilograms by the square of height in meters. BMI is relevant for medical prognostication as it serves as a quick, low-cost, and reliable screening tool for body composition, risk of type 2 diabetes, metabolic syndrome and specific cancers.

BMI and cardiovascular outcomes

  • High BMI is associated with several health conditions:
  • Type 2 diabetes
  • Hypertension
  • Coronary artery disease
  • Heart failure
  • Dyslipidemia (including high LDL, total cholesterol and triglycerides)
  • Atrial fibrillation

    BMI categories

    The World Health Organization defines BMI categories as follows:

    Underweight: Less than 18.5

    Normal weight: 18.5 to 24.9

    Overweight: 25 to 29.9

    Obese: 30 and above

    Limitations of BMI

    Despite its widespread use, BMI has several limitations:

    • It does not distinguish between fat, muscle, and bone mass.
    • It does not indicate the types or distribution of body fat.
    • It may not be accurate for all populations, particularly at the extremes of height and weight.
    • BMI is particularly poor a predictor in South Asians, who have substantially elevated risk of cardiovascular disease and diabetes at BMI levels of 23 kg/m2 or higher.

    Body surface area (BSA)

    Body Surface Area is the total surface area of the body. It is often used in clinical settings because it is considered a more accurate indicator of metabolic mass than body weight alone.

    BSA is utilized in various medical applications:

    • Calculation of drug dosages, particularly in chemotherapy
    • Determination of fluid administration
    • Assessment of various hemodynamic and echocardiographic parameters.
    Updated on 2025-01-18