Calculate total surface area using the Mosteller formula
Estimated Body Surface Area
0.00 m²
What is Body Surface Area (BSA)?
Body Surface Area (BSA) is the measured or calculated surface of a human body. In clinical medicine, BSA is often considered a more accurate indicator of metabolic mass than body weight alone because it is less affected by abnormal adipose tissue (body fat).
Physicians and pharmacists use BSA calculations to determine precise dosages for high-risk medications, such as chemotherapy drugs, steroids, and certain antibiotics. It is also a critical metric in cardiovascular physiology to calculate the cardiac index.
The Mosteller Formula
While several formulas exist (including DuBois, Haycock, and Gehan-George), this calculator utilizes the Mosteller formula. Published in 1987, it is the most widely used formula due to its simplicity and accuracy across various body types.
BSA (m²) = √([Height (cm) × Weight (kg)] / 3600)
Why Use BSA Instead of Weight?
Dosing based solely on weight can lead to over-medication in obese patients or under-medication in very lean patients. BSA accounts for the relationship between height and weight, providing a better proxy for a patient's fluid requirements and metabolic rate.
Practical Examples
Example 1: An adult weighing 80 kg with a height of 180 cm.
Calculation: √((180 × 80) / 3600) = √(14400 / 3600) = √4 = 2.00 m².
Example 2: A child weighing 30 kg with a height of 130 cm.
Calculation: √((130 × 30) / 3600) = √(3900 / 3600) = √1.083 = 1.04 m².
Clinical Importance
The average adult BSA is generally considered to be 1.73 m² (standardized for a 70kg male). Understanding your BSA can help in monitoring health metrics, but it is primarily a tool for medical professionals. Always consult with a healthcare provider before making any medical decisions based on these calculations.
function calculateBSA() {
var weight = document.getElementById('weightInput').value;
var height = document.getElementById('heightInput').value;
var resultArea = document.getElementById('bsa-result-area');
var bsaDisplay = document.getElementById('bsaValue');
var noteDisplay = document.getElementById('bsaNote');
var w = parseFloat(weight);
var h = parseFloat(height);
if (isNaN(w) || isNaN(h) || w <= 0 || h <= 0) {
alert("Please enter valid positive numbers for both weight and height.");
resultArea.style.display = "none";
return;
}
// Mosteller Formula: sqrt((height * weight) / 3600)
var bsa = Math.sqrt((h * w) / 3600);
var formattedBSA = bsa.toFixed(2);
bsaDisplay.innerHTML = formattedBSA + " m²";
var comparison = "";
if (bsa 1.9) {
comparison = "This is above the average adult surface area.";
} else {
comparison = "This is within the typical range for adults.";
}
noteDisplay.innerHTML = comparison;
resultArea.style.display = "block";
}