Linear feet to square feet is one of the most common conversions in construction, home improvement, and material purchasing. If you know the length of a material (in linear feet) and its width, you can calculate the total area it covers in square feet. This is essential for ordering flooring, decking, siding, drywall, and any material sold by the linear foot that covers a surface.
The key concept: linear feet measures length only. Square feet requires width. Without knowing the width of your material, you cannot make this conversion.
Linear Feet to Square Feet
Convert linear feet to square footage
Linear Feet → Square Feet
Square Feet
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Square Feet → Linear Feet
Linear Feet
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How to Convert Linear Feet to Square Feet
The formula to convert linear feet to square feet is:
Critical rule: width must be in feet. If your material width is in inches, divide by 12 first. A 6-inch-wide board = 6 / 12 = 0.5 feet. Using inches directly will give wildly incorrect results.
Step-by-Step Worked Examples
| Linear Feet | Width (in) | Width (ft) | Square Feet | Real-World Use |
|---|---|---|---|---|
| 10 | 36" | 3 | 30 | Roll of 3-ft-wide carpet |
| 20 | 48" | 4 | 80 | 4-ft-wide drywall sheets |
| 50 | 24" | 2 | 100 | 2-ft-wide roll roofing |
| 100 | 18" | 1.5 | 150 | 18-inch-wide siding panels |
| 350 | 5.5" | 0.458 | 160.4 | Deck boards (standard 5/4×6) |
| 480 | 3.5" | 0.292 | 140 | Hardwood floor planks (3.5") |
When Do You Need to Convert Linear Feet to Square Feet?
Ordering Flooring
Flooring is priced by the square foot, but individual planks or tiles are measured by their length (linear feet). A box of hardwood flooring might contain 20 linear feet of 3.5-inch-wide planks. Square footage per box = 20 LF × (3.5 / 12) = 5.83 SF. Knowing this conversion lets you compare prices across different plank widths and calculate exactly how many boxes you need for a 200 SF room.
Estimating Paint or Stain Coverage
Paint and stain coverage is rated in square feet per gallon (typically 250–400 SF/gal). If you're painting a fence built from 1×6 pickets (5.5" actual width) spanning 300 linear feet, the surface area is 300 × (5.5/12) = 137.5 SF per side. For both sides: 275 SF. That's approximately one gallon of stain — much less than the 600+ SF you might guess if you forget to convert from linear to square feet.
Siding and Exterior Cladding
Vinyl and fiber cement siding is sold by the box, with each piece having a specific exposure width and length. A box of 12-foot siding panels with a 6-inch exposure covers 6 SF per panel. If your house exterior is 1,500 SF and each box covers 200 SF, you need 8 boxes. Without the LF to SF conversion, you'd either order too little (wasting time and delivery fees) or too much (wasting hundreds of dollars in unused material).
Carpet and Roll Flooring
Carpet is sold in 12-foot and 15-foot wide rolls, priced by the square foot. A 20-linear-foot piece of 12-foot-wide carpet covers 240 SF. But carpet must be installed in one direction (no cross-seams), so a 12×14 room needs two pieces at 14 LF each = 28 LF of carpet, covering 336 SF total (with waste). The LF to SF conversion helps you separate the usable area from the waste and compare installed cost per usable square foot.
Common Material Widths — Quick Reference
Most building materials come in standard widths. Knowing these makes LF-to-SF conversion fast:
| Material | Typical Width (in) | Width (ft) | SF per 10 LF | Notes |
|---|---|---|---|---|
| Deck board (5/4×6) | 5.5 | 0.458 | 4.58 | Standard residential decking |
| Hardwood flooring | 3–5 | 0.25–0.417 | 2.5–4.17 | Varies by manufacturer |
| Drywall sheet | 48 | 4 | 40 | 4'×8' standard sheet |
| Vinyl siding panel | 6–8 | 0.5–0.667 | 5–6.67 | Exposure width (not total) |
| Carpet roll | 144–180 | 12–15 | 120–150 | Standard roll widths |
| Roll roofing | 36 | 3 | 30 | Mineral-surfaced roll |