The total length of material measured in a straight line.
The width of a single board or plank in inches.
Total Area: 0.00 sq. ft.
Estimated Material Cost: $0.00
Conversion Factor: 0 sq. ft. per linear foot
function calculateSquareFootage() {
// 1. Get input values
var lf = parseFloat(document.getElementById('linearFeetInput').value);
var widthInches = parseFloat(document.getElementById('materialWidthInput').value);
var pricePerLF = parseFloat(document.getElementById('pricePerLFInput').value);
// 2. DOM elements for results
var resultBox = document.getElementById('resultDisplay');
var errorBox = document.getElementById('errorMessage');
var sqFtDisplay = document.getElementById('sqFtResult');
var costDisplay = document.getElementById('totalCostResult');
var costRow = document.getElementById('costResultRow');
var factorDisplay = document.getElementById('conversionFactor');
// 3. Reset display
errorBox.style.display = 'none';
resultBox.style.display = 'none';
costRow.style.display = 'none';
// 4. Validation
if (isNaN(lf) || lf <= 0) {
errorBox.innerText = "Please enter a valid number for Linear Feet.";
errorBox.style.display = 'block';
return;
}
if (isNaN(widthInches) || widthInches 0) {
totalCost = lf * pricePerLF;
costRow.style.display = 'block';
costDisplay.innerText = '$' + totalCost.toFixed(2);
}
// 6. Display Results
sqFtDisplay.innerText = totalSqFt.toFixed(2);
factorDisplay.innerText = widthInFeet.toFixed(4);
resultBox.style.display = 'block';
}
How to Calculate Square Footage from Linear Feet
Understanding the difference between Linear Feet (LF) and Square Footage (SF) is crucial for home improvement projects involving decking, flooring, siding, or lumber. While linear feet measures a 1-dimensional length, square footage measures a 2-dimensional area. To convert between them, you must account for the width of the material you are using.
The Conversion Formula
You cannot convert linear feet directly to square feet without knowing the width of the board. The standard formula requires converting the width from inches to feet first, then multiplying by the length.
Formula: Square Footage = Linear Feet × (Width in Inches ÷ 12)
Step-by-Step Calculation Example
Let's say you are purchasing wood planks for a deck. You have 500 linear feet of planking, and each plank is 6 inches wide.
Convert Width to Feet: Divide the width (6 inches) by 12.
6 ÷ 12 = 0.5 feet.
Multiply by Linear Feet: Multiply the width in feet by the total linear feet.
0.5 feet × 500 LF = 250 Square Feet.
Why Does This Matter?
Materials are sold in different units. Lumber is often sold by the linear foot, but the area you need to cover (like a room or deck) is measured in square feet. This calculator bridges that gap, ensuring you order the correct amount of material without significant waste.
Common Material Widths
2×4 Lumber: Actual width is 3.5 inches.
2×6 Lumber: Actual width is 5.5 inches.
Standard Decking: Often 5.5 inches wide.
Flooring Planks: Varies widely, usually between 2.25 inches and 8 inches.
Estimating Costs
Once you know the conversion, you can compare costs more effectively. Sometimes pricing is listed per linear foot, while other times it is per square foot. By converting your linear footage order into square footage, you can determine the true cost per unit of area coverage.
Note: Always remember to add 10-15% extra material for waste, cuts, and mistakes when planning your construction projects.