Karl Mortgage Calculator

Body Surface Area (BSA) Calculator

Your Estimated BSA (Mosteller):

0.00 m²

function calculateBSA() { var height = parseFloat(document.getElementById('bsa_height').value); var weight = parseFloat(document.getElementById('bsa_weight').value); var resultContainer = document.getElementById('bsa_result_container'); var resultDisplay = document.getElementById('bsa_value'); var interpretation = document.getElementById('bsa_interpretation'); if (isNaN(height) || isNaN(weight) || height <= 0 || weight <= 0) { alert("Please enter valid positive numbers for height and weight."); return; } // Mosteller Formula: BSA = sqrt( (Height(cm) * Weight(kg)) / 3600 ) var bsa = Math.sqrt((height * weight) / 3600); var bsaFixed = bsa.toFixed(2); resultDisplay.innerHTML = bsaFixed + " m²"; var infoText = ""; if (bsa = 1.6 && bsa <= 1.9) { infoText = "This is within the average range for most adults."; } else { infoText = "This is above the average range for most adults."; } interpretation.innerHTML = infoText; resultContainer.style.display = 'block'; }

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What is Body Surface Area (BSA)?

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

Why is BSA Important?

Medical professionals use BSA for several critical purposes:

• Medication Dosing: Many chemotherapy drugs and specialized medications are calculated based on m² rather than kg to ensure therapeutic efficacy while minimizing toxicity.
• Cardiac Index: Relates the cardiac output to the BSA to better assess a patient's heart function relative to their size.
• Renal Function: The Glomerular Filtration Rate (GFR) is often adjusted to the average BSA (1.73 m²).
• Burn Assessment: Used to determine the severity of burns and fluid resuscitation requirements.

The Mosteller Formula

While several formulas exist (such as Du Bois or Haycock), this calculator utilizes the Mosteller Formula, which is the most widely adopted due to its simplicity and accuracy across different body types. The math is simple:

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

Example Calculation

If an individual weighs 80 kg and stands 180 cm tall, the calculation would look like this:

1. Multiply height by weight: 180 × 80 = 14,400
2. Divide by 3,600: 14,400 / 3,600 = 4
3. Take the square root of 4: √4 = 2.00 m²

Normal Reference Ranges

The "average" body surface area varies depending on age and biological sex:

Category	Average BSA
Adult Men	1.9 m²
Adult Women	1.6 m²
Children (9 years)	1.07 m²
Neonates	0.25 m²

Note: This calculator is for educational purposes only. Clinical decisions should always be made by a qualified healthcare professional.