What Is a Linear Foot?
Part of Area & Volume
Quick answer
A linear foot is simply 12 inches of length measured in a straight line — its width and thickness don't count. Materials priced by the linear foot (lumber, trim, fencing, countertops, pipe) are sold by length alone, so two boards of different widths can cost the same per linear foot.
"Linear" just means "in a line." A linear foot (also called a lineal foot) is one foot of length — nothing more. It ignores how wide or thick the material is, which is why it's the natural unit for anything you buy by the running length.
Linear feet vs. square feet vs. board feet
- Linear foot — length only (1 ft). Used for trim, fencing, pipe, lumber by the stick.
- Square foot — area (length × width). Used for flooring, drywall, paint coverage.
- Board foot — volume (length × width × thickness). Used for rough hardwood lumber.
Materials sold by the linear foot
- Dimensional lumber, trim, molding and baseboard.
- Fencing, railing and decking boards.
- Countertops, cabinets and shelving.
- Pipe, conduit, gutter and wire.
Turning area into linear feet
When a job is measured in square feet but the material is sold by the linear foot (flooring or decking, say), divide the area by the board's width in feet. The table shows how many linear feet cover 100 ft² at common board widths.
| Board width | Linear feet per 100 ft² |
|---|---|
| 3.5 in (1×4) | 343 lin ft |
| 5.5 in (1×6) | 218 lin ft |
| 7.25 in (1×8) | 166 lin ft |
| 11.25 in (1×12) | 107 lin ft |
FAQs
Is a linear foot the same as a foot?
Yes. A linear foot and a foot are the same 12-inch length. "Linear" is added only to make clear you're measuring straight-line length, not area (square feet) or volume (cubic feet).
How is a linear foot different from a square foot?
A linear foot measures length only. A square foot measures area — length times width. You can't convert between them without knowing the width of the material.