Personal Interest Rate Calculator

Body Surface Area (BSA) Calculator

Mosteller (Standard) DuBois and DuBois Haycock Gehan and George

Calculated BSA:

Please enter valid positive numbers for height and weight.

function calculateBSA() { var weight = parseFloat(document.getElementById('bsaWeight').value); var weightUnit = document.getElementById('weightUnit').value; var height = parseFloat(document.getElementById('bsaHeight').value); var heightUnit = document.getElementById('heightUnit').value; var formula = document.getElementById('bsaFormula').value; var resultDiv = document.getElementById('bsaResult'); var errorDiv = document.getElementById('bsaError'); var valueDisplay = document.getElementById('bsaValue'); var formulaDisplay = document.getElementById('formulaUsedDisplay'); if (isNaN(weight) || isNaN(height) || weight <= 0 || height <= 0) { resultDiv.style.display = 'none'; errorDiv.style.display = 'block'; return; } errorDiv.style.display = 'none'; // Convert to Metric (kg and cm) if necessary var weightKg = (weightUnit === 'lb') ? weight * 0.453592 : weight; var heightCm = (heightUnit === 'in') ? height * 2.54 : height; var bsa = 0; var formulaName = ""; if (formula === 'mosteller') { // Mosteller: sqrt( (height cm * weight kg) / 3600 ) bsa = Math.sqrt((heightCm * weightKg) / 3600); formulaName = "Mosteller Formula"; } else if (formula === 'dubois') { // DuBois: 0.007184 * weight^0.425 * height^0.725 bsa = 0.007184 * Math.pow(weightKg, 0.425) * Math.pow(heightCm, 0.725); formulaName = "DuBois and DuBois Formula"; } else if (formula === 'haycock') { // Haycock: 0.024265 * weight^0.5378 * height^0.3964 bsa = 0.024265 * Math.pow(weightKg, 0.5378) * Math.pow(heightCm, 0.3964); formulaName = "Haycock Formula"; } else if (formula === 'gehan') { // Gehan & George: 0.0235 * weight^0.51456 * height^0.42246 bsa = 0.0235 * Math.pow(weightKg, 0.51456) * Math.pow(heightCm, 0.42246); formulaName = "Gehan and George Formula"; } valueDisplay.innerHTML = bsa.toFixed(2) + " m²"; formulaDisplay.innerHTML = "Based on the " + formulaName; resultDiv.style.display = 'block'; }

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Understanding Body Surface Area (BSA)

Body Surface Area (BSA) is the measured or calculated surface of a human body. For many clinical purposes, BSA is a better indicator of metabolic mass than body weight because it is less affected by abnormal adipose tissue (body fat). In clinical practice, BSA is most commonly used to calculate dosages for chemotherapy and other high-risk medications, as well as to index cardiac output and other physiological parameters.

Why use BSA instead of Weight?

While weight is easy to measure, it doesn't always reflect the patient's metabolic capacity. Two patients might weigh the same, but one might be much taller and leaner than the other. The taller patient has a different distribution of fluid and metabolic activity. BSA accounts for both height and weight, providing a more balanced metric for:

• Chemotherapy Dosing: Most oncologists use BSA to ensure toxic drugs are administered in precise amounts relative to the patient's size.
• Renal Function: The Glomerular Filtration Rate (GFR) is often normalized to a standard BSA of 1.73 m².
• Cardiac Index: Relates the heart's performance (cardiac output) to the patient's size.
• Burn Assessment: Determining the extent of skin damage in burn victims.

Common BSA Formulas

Several formulas exist to calculate BSA. The most widely used is the Mosteller formula due to its simplicity. However, different clinical settings may prefer others:

Formula	Calculation Method
Mosteller	Square root of ([Height in cm × Weight in kg] / 3600)
DuBois	0.007184 × Weight^0.425 × Height^0.725
Haycock	Commonly used for infants and children.

Calculation Examples

To see how BSA varies, consider these realistic scenarios:

Example 1 (Average Adult):
Height: 175 cm (5'9″) | Weight: 70 kg (154 lbs)
Using Mosteller: sqrt((175 * 70) / 3600) = 1.84 m²

Example 2 (Large Adult):
Height: 190 cm (6'3″) | Weight: 100 kg (220 lbs)
Using Mosteller: sqrt((190 * 100) / 3600) = 2.30 m²

Disclaimer: This calculator is for educational purposes only. Medical decisions and medication dosages should always be verified by a licensed healthcare professional. The average adult BSA is generally considered to be 1.73 m².