How Do I Calculate Linear Feet from Square Feet

Square Feet to Linear Feet Calculator

Note: A standard 1×6 board is actually 5.5 inches wide.

Total Linear Feet Needed: 0 LF

function calculateLinearFeet() { var sqft = document.getElementById('totalSqFt').value; var widthInches = document.getElementById('materialWidth').value; var resultDiv = document.getElementById('lf-result'); var output = document.getElementById('outputValue'); var wasteText = document.getElementById('wasteAdjustment'); if (sqft > 0 && widthInches > 0) { // Convert width from inches to feet var widthFeet = widthInches / 12; // Formula: Linear Feet = Square Feet / Width (in feet) var linearFeet = sqft / widthFeet; // 10% Waste Factor var wasteTotal = linearFeet * 1.10; output.innerHTML = linearFeet.toFixed(2); wasteText.innerHTML = "Including a 10% waste factor for cuts, you should order " + wasteTotal.toFixed(2) + " linear feet."; resultDiv.style.display = 'block'; } else { alert("Please enter valid positive numbers for both fields."); } }

Understanding Linear Feet vs. Square Feet

When planning a home improvement project—whether it's installing hardwood floors, building a deck, or putting up a fence—you will likely encounter two primary measurements: square feet (SF) and linear feet (LF). While square feet measures the two-dimensional area of a surface, linear feet measures the one-dimensional length of the material.

The Conversion Formula

To calculate linear feet from square feet, you must know the width of the material you are using. Because square feet is Length × Width, you can find the length by dividing the total area by the width. However, since material width is usually measured in inches, you must first convert that width into feet.

The Math:
1. Width in Feet = Width in Inches ÷ 12
2. Linear Feet = Total Square Feet ÷ Width in Feet

Real-World Example: Building a Deck

Suppose you are building a deck that is 200 square feet. You have decided to use standard "1×6" decking boards. It is crucial to remember that "nominal" sizes differ from "actual" sizes. A 1×6 board is actually 5.5 inches wide.

• Step 1: Convert 5.5 inches to feet (5.5 / 12 = 0.458 feet).
• Step 2: Divide the area by the width (200 / 0.458 = 436.68).
• Result: You need approximately 437 linear feet of decking material.

Common Material Widths (Actual vs. Nominal)

Nominal Size	Actual Width (Inches)	Common Use
1×4	3.5″	Trim / Fencing
1×6	5.5″	Decking / Siding
1×8	7.25″	Baseboards / Fascia

Don't Forget the Waste Factor

In construction, you should never order the exact amount of material calculated. Between cutting errors, knots in the wood, and staggering joints, you will lose a portion of your material. It is industry standard to add 10% to 15% to your final linear footage calculation to ensure you have enough to finish the job without another trip to the lumber yard.