Identify the Formula to Calculate a Budgeted Indirect Cost Rate

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Body Surface Area (BSA) Calculator

Calculated BSA (Mosteller Formula):
function calculateBSA() { var h = parseFloat(document.getElementById('height_cm').value); var w = parseFloat(document.getElementById('weight_kg').value); var resultBox = document.getElementById('bsa_result_box'); var resultValue = document.getElementById('bsa_value'); var comparison = document.getElementById('bsa_comparison'); if (isNaN(h) || isNaN(w) || h <= 0 || w <= 0) { alert('Please enter valid positive numbers for height and weight.'); return; } // Mosteller Formula: sqrt((Height x Weight) / 3600) var bsa = Math.sqrt((h * w) / 3600); resultValue.innerHTML = bsa.toFixed(2) + " m²"; var avgMale = 1.9; var avgFemale = 1.6; comparison.innerHTML = "Average adult male: ~1.9 m² | Average adult female: ~1.6 m²"; resultBox.style.display = 'block'; }

What is Body Surface Area (BSA)?

Body Surface Area (BSA) is the measured or calculated surface area of a human body. In clinical medicine, BSA is often considered a more accurate indicator of metabolic mass than body weight because it is less affected by abnormal adipose tissue (fat).

Why is BSA Important in Medicine?

Medical professionals use BSA for several critical clinical purposes, including:

  • Dosage Calculation: Many potent drugs, especially chemotherapy agents and monoclonal antibodies, are dosed based on m² rather than weight alone to minimize toxicity.
  • Cardiac Index: The cardiac output is often divided by the BSA to determine the cardiac index, providing a better view of a patient's heart performance relative to their size.
  • Glomerular Filtration Rate (GFR): BSA is used to normalize GFR results to assess kidney function accurately.
  • Burn Assessment: Determining the extent of skin damage in burn victims often references body surface percentages.

How BSA is Calculated

This calculator uses the Mosteller Formula, which is the most widely accepted and easiest to use in clinical settings. The formula is:

BSA (m²) = √([Height (cm) × Weight (kg)] / 3600)

Other formulas exist, such as the Du Bois formula (0.007184 × Weight0.425 × Height0.725), but research shows the Mosteller method provides nearly identical results with simpler arithmetic.

Practical Example

If an adult patient stands 180 cm tall and weighs 85 kg, the calculation would be:

  1. Multiply height by weight: 180 × 85 = 15,300
  2. Divide by 3,600: 15,300 / 3,600 = 4.25
  3. Find the square root: √4.25 = 2.06 m²

Frequently Asked Questions (FAQ)

Is BSA better than BMI?
While BMI (Body Mass Index) is useful for identifying obesity or malnutrition in the general population, BSA is superior for clinical pharmacology and physiological measurements because it correlates better with blood volume and metabolic rate.

What is the average BSA?
The average adult man has a BSA of approximately 1.9 m², while the average adult woman has a BSA of approximately 1.6 m². For neonates (newborns), the average is roughly 0.25 m².

Disclaimer: This calculator is intended for educational and informational purposes only. It should not be used as a substitute for professional medical advice, diagnosis, or treatment. Always consult with a qualified healthcare provider for clinical dosing or medical decisions.

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