function toggleInputs() {
var shape = document.getElementById("roomShape").value;
var rectDiv = document.getElementById("rect-inputs");
var circleDiv = document.getElementById("circle-inputs");
var widthLabel = document.getElementById("widthLabel");
var widthInLabel = document.getElementById("widthInLabel");
if (shape === "circle") {
rectDiv.style.display = "none";
circleDiv.style.display = "block";
} else if (shape === "triangle") {
rectDiv.style.display = "block";
circleDiv.style.display = "none";
widthLabel.innerHTML = "Base (Feet)";
widthInLabel.innerHTML = "Base (Inches)";
} else {
rectDiv.style.display = "block";
circleDiv.style.display = "none";
widthLabel.innerHTML = "Width (Feet)";
widthInLabel.innerHTML = "Width (Inches)";
}
}
function calculateSqFt() {
var shape = document.getElementById("roomShape").value;
var price = parseFloat(document.getElementById("price_per_sqft").value) || 0;
var totalSqFt = 0;
if (shape === "rectangle" || shape === "triangle") {
var lFt = parseFloat(document.getElementById("len_ft").value) || 0;
var lIn = parseFloat(document.getElementById("len_in").value) || 0;
var wFt = parseFloat(document.getElementById("wid_ft").value) || 0;
var wIn = parseFloat(document.getElementById("wid_in").value) || 0;
var length = lFt + (lIn / 12);
var width = wFt + (wIn / 12);
if (shape === "rectangle") {
totalSqFt = length * width;
} else {
totalSqFt = (length * width) / 2;
}
} else if (shape === "circle") {
var rFt = parseFloat(document.getElementById("rad_ft").value) || 0;
var rIn = parseFloat(document.getElementById("rad_in").value) || 0;
var radius = rFt + (rIn / 12);
totalSqFt = Math.PI * Math.pow(radius, 2);
}
var displayResult = document.getElementById("results-box");
var sqftOutput = document.getElementById("sqft-output");
var costOutput = document.getElementById("cost-output");
if (totalSqFt > 0) {
displayResult.style.display = "block";
sqftOutput.innerHTML = totalSqFt.toFixed(2) + " sq ft";
if (price > 0) {
var totalCost = totalSqFt * price;
costOutput.innerHTML = "Estimated Total Cost: $" + totalCost.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
} else {
costOutput.innerHTML = "";
}
} else {
alert("Please enter valid dimensions greater than zero.");
displayResult.style.display = "none";
}
}
How to Calculate Square Feet: A Complete Guide
Calculating square footage is a fundamental skill for homeowners, renters, and DIY enthusiasts. Whether you are ordering new hardwood flooring, buying mulch for your garden, or painting a bedroom, knowing the exact area ensures you buy the right amount of materials and stay within budget.
The Standard Formula
For most standard rooms, the calculation is simple. The basic formula for a rectangular area is:
Length (ft) × Width (ft) = Total Square Feet (sq ft)
Calculating Different Room Shapes
Not every space is a perfect rectangle. Here is how to handle various geometries:
- Triangular Spaces: Multiply the base length by the height and divide by two. This is common in corner gardens or attic spaces.
- Circular Areas: Measure from the center to the edge (radius). Multiply the radius by itself (square it), then multiply by Pi (3.14159).
- Irregular L-Shapes: Divide the room into two or more rectangles. Calculate the square footage of each section individually and add them together.
Pro-Tips for Accuracy
Convert Inches to Feet First: If your measurement includes inches, divide the inch count by 12. For example, 10 feet 6 inches becomes 10.5 feet (6 / 12 = 0.5). Our calculator above handles this conversion for you automatically.
The "Waste Factor": When ordering materials like tile or laminate flooring, it is standard practice to add a 10% waste factor. This accounts for cuts, mistakes, and future repairs. To calculate this, simply multiply your total square footage by 1.10.
Real-World Example
Imagine you have a living room that is 15 feet 4 inches long and 12 feet wide.
- Convert the length: 15 + (4 / 12) = 15.33 feet.
- Multiply: 15.33 ft × 12 ft = 183.96 sq ft.
- If the flooring costs $5.00 per square foot, your total cost would be 183.96 × 5 = $919.80.