Linear to Square Foot Calculator

Total Linear Feet:

Width of Material (Inches):

function calculateSqFt() { var linFeet = parseFloat(document.getElementById('linFeet').value); var widthInches = parseFloat(document.getElementById('widthInches').value); var resultDiv = document.getElementById('resultDisplay'); if (isNaN(linFeet) || isNaN(widthInches) || linFeet <= 0 || widthInches <= 0) { resultDiv.style.display = 'block'; resultDiv.style.backgroundColor = '#ffebee'; resultDiv.style.color = '#c62828'; resultDiv.innerHTML = 'Please enter valid positive numbers for both fields.'; return; } // Convert width from inches to feet var widthFeet = widthInches / 12; // Formula: Linear Feet * (Width in Inches / 12) = Square Feet var sqFt = linFeet * widthFeet; resultDiv.style.display = 'block'; resultDiv.style.backgroundColor = '#e7f3ff'; resultDiv.style.color = '#0056b3'; resultDiv.innerHTML = 'Total Area: ' + sqFt.toFixed(2) + ' Square Feet'; }

Understanding Linear Feet vs. Square Feet

When planning a home improvement project, such as installing new hardwood floors, decking, or siding, you will often encounter two different units of measurement: linear feet and square feet. Understanding the difference is crucial for ordering the correct amount of material and staying within your budget.

What is a Linear Foot?

A linear foot is a measure of length. It is simply 12 inches in a straight line. It does not take into account the width or thickness of the object. For example, if you have a 10-foot long board, you have 10 linear feet, regardless of whether that board is 2 inches wide or 12 inches wide.

What is a Square Foot?

A square foot is a measure of area. It accounts for both length and width (Length x Width). This is the standard measurement used to determine the surface area of a floor, wall, or ceiling.

The Conversion Formula

To convert linear feet to square feet, you must know the width of the material you are using. Since most building materials (like decking boards) have widths measured in inches, you must first convert that width into feet.

The Formula:
Square Feet = Linear Feet × (Width in Inches / 12)

Practical Example: Decking Project

Imagine you are building a deck and you have purchased 200 linear feet of 6-inch wide cedar boards. To find out how much surface area this will cover, follow these steps:

Step 1: Identify linear feet (200).
Step 2: Identify width in inches (6).
Step 3: Convert width to feet (6 / 12 = 0.5 feet).
Step 4: Multiply linear feet by width in feet (200 × 0.5 = 100).

In this case, your 200 linear feet of boards will cover 100 square feet of deck space.

Common Material Width Conversions

Below are common widths for construction materials converted into their decimal foot equivalent to help with manual calculations:

Nominal Width (Inches)	Width in Feet
3 Inches	0.25 ft
4 Inches	0.33 ft
6 Inches	0.50 ft
8 Inches	0.66 ft
12 Inches	1.00 ft

Why Use This Calculator?

Using a Linear to Square Foot Calculator eliminates the risk of "math fatigue" during project planning. Accurate measurements ensure you don't over-purchase (wasting money) or under-purchase (causing project delays). It is particularly helpful for materials sold by the "running foot" or "linear foot" like trim, baseboards, and specialized lumber.