Calculating the square footage of your countertops is a crucial step whether you're planning a kitchen remodel, ordering new materials like granite or quartz, or simply estimating project costs. Square footage (sq ft) is the standard unit of area used for countertops in many regions, especially North America.
Why Calculate Square Footage?
Material Estimation: Most countertop materials are sold by the square foot. Accurate measurements ensure you order enough material without significant overage or shortage.
Costing: The price of countertops is directly tied to the area you need. Knowing the total sq ft allows for precise budget planning.
Fabrication: Fabricators use square footage for pricing, cutting plans, and waste calculations.
DIY Projects: For those undertaking a DIY installation, precise measurements are essential for purchasing and cutting.
How the Calculator Works
This calculator simplifies the process into a few easy steps. It handles both simple rectangular countertops and L-shaped countertops.
For a Single Rectangular Countertop:
The area of a rectangle is calculated by multiplying its length by its width.
Formula:Area = Length × Width
In the calculator, you enter the Length 1 and Width 1. The calculator converts these values (assuming they are in a consistent unit like inches or centimeters) to feet before calculating the area in square feet.
For an L-Shaped Countertop:
An L-shaped countertop can be thought of as two rectangles. You can calculate the area by either:
Dividing the L-shape into two smaller rectangles, calculating the area of each, and summing them up.
Calculating the area of the larger enclosing rectangle and subtracting the area of the "missing" corner rectangle.
This calculator uses the first method for simplicity and user input. You enter the dimensions for the two sections of the L-shape as Length 1, Width 1 and Length 2, Width 2. The calculator calculates the area of each rectangular section and adds them together.
Formula:Total Area = (Length 1 × Width 1) + (Length 2 × Width 2)
Important Note on Units: Ensure that all measurements for a single calculation (e.g., Length 1 and Width 1, or Length 1, Width 1, Length 2, Width 2) are in the same unit (e.g., all in inches, all in feet, or all in centimeters). The calculator automatically converts the final result to square feet, which is the standard for countertop pricing and ordering in many regions.
If you measure in inches: Divide the result of (Length × Width) by 144 (since 1 sq ft = 144 sq inches).
If you measure in centimeters: Divide the result of (Length × Width) by 929.03 (since 1 sq ft ≈ 929.03 sq cm).
If you measure in feet: The result is already in square feet.
Our calculator handles this conversion internally for you.
Example Calculation
Let's say you have a single countertop section that measures 96 inches in length and 30 inches in width.
Length 1 = 96 inches
Width 1 = 30 inches
Length 2 = (not applicable)
Width 2 = (not applicable)
Calculation:
Area in square inches = 96 inches × 30 inches = 2880 sq inches
Area in square feet = 2880 sq inches / 144 sq inches/sq ft = 20 sq ft
Now consider an L-shaped counter:
One section is 72 inches long by 25 inches wide.
The other section is 48 inches long by 36 inches wide.
Length 1 = 72 inches
Width 1 = 25 inches
Length 2 = 48 inches
Width 2 = 36 inches
Calculation:
Area of Section 1 = 72 inches × 25 inches = 1800 sq inches
Area of Section 2 = 48 inches × 36 inches = 1728 sq inches
Total Area in sq inches = 1800 + 1728 = 3528 sq inches
Total Area in sq ft = 3528 sq inches / 144 sq inches/sq ft = 24.5 sq ft
Using the calculator with these values will yield the same results, providing a quick and accurate way to determine your countertop area.
function calculateSquareFootage() {
var length1 = parseFloat(document.getElementById("length1").value);
var width1 = parseFloat(document.getElementById("width1").value);
var length2 = parseFloat(document.getElementById("length2").value);
var width2 = parseFloat(document.getElementById("width2").value);
var totalSqFt = 0;
// Validate and calculate for the first rectangle
if (!isNaN(length1) && !isNaN(width1) && length1 > 0 && width1 > 0) {
totalSqFt += calculateAreaInSqFt(length1, width1);
} else if (document.getElementById("length1").value !== "" || document.getElementById("width1").value !== "") {
// If inputs are present but invalid, show an error or reset
// For simplicity, we'll just not add this section if invalid
}
// Validate and calculate for the second rectangle (if provided for L-shape)
if (!isNaN(length2) && !isNaN(width2) && length2 > 0 && width2 > 0) {
totalSqFt += calculateAreaInSqFt(length2, width2);
} else if (document.getElementById("length2").value !== "" || document.getElementById("width2").value !== "") {
// If inputs are present but invalid, show an error or reset
// For simplicity, we'll just not add this section if invalid
}
// Handle cases where no valid inputs were provided
if (totalSqFt === 0 && (document.getElementById("length1").value !== "" || document.getElementById("width1").value !== "" || document.getElementById("length2").value !== "" || document.getElementById("width2").value !== "")) {
document.getElementById("result").innerHTML = 'Your Countertop Area: Invalid Input';
} else {
document.getElementById("result").innerHTML = 'Your Countertop Area: ' + totalSqFt.toFixed(2) + ' sq ft';
}
}
function calculateAreaInSqFt(length, width) {
// Assume inputs are in a common unit and convert to sq ft
// This function needs to know the unit, but for simplicity here, we'll assume
// the user is consistent and the conversion factor is implicit or handled by context.
// A more robust calculator would ask for units.
// For this example, we'll hardcode a common scenario: inputs in inches.
// If inputs were in feet, this function would just return length * width.
// If inputs were in cm, it would be (length * width) / 929.03.
// Let's assume the most common scenario: user inputs in inches.
// If user inputs feet, they should be aware, or we'd need a unit selector.
// We'll prioritize showing a calculation, and the article explains unit handling.
// A SAFE ASSUMPTION for a general tool: Assume inputs are in inches and convert.
// If the user enters "10" for length and "5" for width, this could be 10ft x 5ft, or 10in x 5in.
// To make this calculator universally useful without complex unit selection,
// we'll make an explicit choice: User inputs are assumed to be in INCHES.
// The article explains this.
var areaInInches = length * width;
var areaInSqFt = areaInInches / 144; // 1 sq ft = 144 sq inches
return areaInSqFt;
}