How to Convert Linear Feet to Square Feet
Understanding the difference between linear footage and square footage is essential for construction projects involving lumber, flooring, decking, or siding. While linear feet measures the straight-line length of a material, square feet measures the total surface area that material covers.
The Conversion Formula
To convert linear feet to square feet, you must first ensure your width is expressed in feet. Since lumber and flooring widths are typically measured in inches, you divide the width by 12.
Step 1: Convert Width to Feet
Width (ft) = Width (inches) ÷ 12
Step 2: Calculate Area
Square Feet = Linear Feet × Width (ft)
Combined Formula:
$$Square Feet = Linear Feet \times \left( \frac{Width_{inches}}{12} \right)$$
Real-World Example: Building a Deck
Imagine you are purchasing decking boards. You have 500 linear feet of standard 6-inch wide deck boards. How much area will this cover?
- Linear Feet: 500 ft
- Board Width: 6 inches
Calculation:
- Convert inches to feet: 6″ ÷ 12 = 0.5 feet.
- Multiply length by width: 500 ft × 0.5 ft = 250 Square Feet.
Why Is This Important?
Most flooring and siding products are sold by the square foot (coverage), but lumber and trim are often sold by the linear foot (length). This calculator bridges the gap between purchasing units and installation coverage.
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 or 6 inches nominal.
- Flooring Planks: Vary widely (2.25″, 3″, 5″, 7″, etc.).
Note: Always use the "actual" width of the board for accurate coverage calculations, not the "nominal" name (e.g., a 2×4 is actually 1.5″ x 3.5″).