Rectangle
Circle
Oval
Irregular (approximate rectangle/average)
Understanding Pool Square Footage
Calculating the square footage of your pool is a fundamental step for various pool-related tasks, including estimating chemical needs, understanding water volume, purchasing covers, planning decking, and comparing pool sizes. The method for calculation depends primarily on the shape of your pool.
Why is Square Footage Important?
Chemicals: Pool chemicals are often dosed based on water volume, which is directly related to surface area and depth. Knowing the square footage helps in accurate estimations.
Covers: When buying a pool cover, you'll need to know the precise dimensions or surface area to ensure a proper fit.
Maintenance: Tasks like cleaning and balancing water chemistry are more efficient when you understand the scale of your pool.
Renovations & Accessories: For projects like installing automatic pool cleaners, heating systems, or building adjacent features like decks or patios, the pool's surface area is a key design parameter.
The Mathematics Behind the Calculation
The core principle for calculating the square footage of a pool is to find its surface area. Here's how it's done for common shapes:
Rectangular Pools: The simplest calculation involves multiplying the length by the width.
Formula: Square Footage = Length × Width
Circular Pools: For a circular pool, you need the radius (the distance from the center to the edge). The area is calculated using Pi (π), approximately 3.14159.
Formula: Square Footage = π × Radius²
Oval Pools: Similar to circles, oval pools use the concept of semi-major and semi-minor axes (or length and width divided by two).
Formula: Square Footage = π × (Length / 2) × (Width / 2)
Irregular Shapes: For pools with non-standard shapes (like L-shapes, kidney beans, or freeform designs), the most practical approach is to:
Break the pool down into simpler geometric shapes (rectangles, triangles, circles).
Calculate the area of each individual shape.
Sum the areas of all the parts to get the total square footage.
Alternatively, you can approximate the pool as a rectangle using its longest and widest points, or by averaging these measurements, but this will yield a less precise result.
How to Use This Calculator
Enter the Length and Width of your pool in feet.
Select the Pool Shape from the dropdown menu.
If you select "Circle" or "Oval", you might need to input the Radius if prompted (for circles, it's half the diameter; for ovals, it's half the major and minor axes, typically derived from Length/2 and Width/2). Our calculator simplifies this by using Length/2 and Width/2 for ovals and expects the radius for circles directly if the shape is selected.
Click the "Calculate Square Footage" button.
The result will be displayed in square feet.
This calculator provides an essential metric for effective pool management and planning.
function calculateSquareFootage() {
var length = parseFloat(document.getElementById("poolLength").value);
var width = parseFloat(document.getElementById("poolWidth").value);
var shape = document.getElementById("poolShape").value;
var radius = parseFloat(document.getElementById("poolRadius").value);
var resultDiv = document.getElementById("result");
var squareFootage = 0;
var calculationDetails = "";
if (isNaN(length) || isNaN(width)) {
resultDiv.innerHTML = "Please enter valid numbers for length and width.";
return;
}
if (shape === "rectangle") {
squareFootage = length * width;
calculationDetails = "Length (" + length + " ft) * Width (" + width + " ft)";
} else if (shape === "circle") {
var diameter = length; // Assuming length is diameter for circle input simplicity
if (isNaN(diameter) || diameter <= 0) {
resultDiv.innerHTML = "Please enter a valid diameter for a circular pool.";
return;
}
radius = diameter / 2;
squareFootage = Math.PI * Math.pow(radius, 2);
calculationDetails = "π * Radius (" + radius + " ft)²";
} else if (shape === "oval") {
var semiMajorAxis = length / 2;
var semiMinorAxis = width / 2;
if (isNaN(semiMajorAxis) || isNaN(semiMinorAxis) || semiMajorAxis <= 0 || semiMinorAxis 0) {
resultDiv.innerHTML = "
Result:
" + squareFootage.toFixed(2) + " sq ft(" + calculationDetails + ")";
} else {
resultDiv.innerHTML = "Calculation could not be performed with the given inputs.";
}
}
document.getElementById("poolShape").addEventListener("change", function() {
var shape = this.value;
var radiusInputGroup = document.getElementById("radius-input-group");
var poolLengthInput = document.getElementById("poolLength");
var poolWidthInput = document.getElementById("poolWidth");
if (shape === "circle") {
radiusInputGroup.style.display = "flex"; // Show radius input
// Clear width input as it's not used for circle, use length as diameter
poolWidthInput.value = "";
poolWidthInput.placeholder = "Diameter (ft)";
poolLengthInput.placeholder = "Diameter (ft)";
} else if (shape === "oval") {
radiusInputGroup.style.display = "none"; // Hide radius input
poolWidthInput.value = ""; // Clear width input, user enters Length & Width as axes
poolWidthInput.placeholder = "Width (ft)";
poolLengthInput.placeholder = "Length (ft)";
}
else {
radiusInputGroup.style.display = "none"; // Hide radius input
poolWidthInput.value = ""; // Clear width input
poolWidthInput.placeholder = "Width (ft)";
poolLengthInput.placeholder = "Length (ft)";
}
});
// Initial setup for shape
document.addEventListener("DOMContentLoaded", function() {
document.getElementById("poolShape").dispatchEvent(new Event("change"));
});