These two units confuse a lot of woodworkers because both have "foot" in the name, but they measure completely different things. A linear foot (also called a running foot) is simply 12 inches of length — it ignores how thick or wide the board is. A board foot is a measure of volume: 144 cubic inches of wood, which accounts for thickness, width, and length together.
If you walk down a board and count off every 12 inches, you are counting linear feet. An 8-foot board is 8 linear feet whether it is a narrow 1″ × 2″ or a wide 2″ × 12″. But those two boards hold very different amounts of wood, so they have very different board-foot counts. Board feet capture that difference; linear feet do not.
| Unit | Typically used for |
|---|---|
| Board foot | Rough hardwood (oak, walnut, maple) sold by volume; pricing lumber where thickness and width vary. |
| Linear foot | Trim, molding, dimensional softwood, dowels, and any product with a fixed cross-section sold by length. |
The rule of thumb: when the cross-section is fixed and known (like a specific molding profile), sellers price by the linear foot. When the cross-section varies board to board (like random-width rough hardwood), they price by the board foot so the value scales with the actual wood you get.
You can convert linear feet to board feet only if you know the thickness and width. The shortcut for a given thickness and width is:
Why divide by 12 instead of 144? Because a linear foot is already 12 inches long, so length is folded in. Examples:
| Board | Per linear foot | 8 ft total |
|---|---|---|
| 1″ × 6″ | (1 × 6) ÷ 12 = 0.50 bf/ft | 4.00 bf |
| 1″ × 12″ | (1 × 12) ÷ 12 = 1.00 bf/ft | 8.00 bf |
| 2″ × 6″ | (2 × 6) ÷ 12 = 1.00 bf/ft | 8.00 bf |
Notice the 1″ × 6″ board: 8 linear feet equals exactly 4.00 board feet, the same answer the full formula gives, because (1 × 6 × 96) ÷ 144 = 4.00. The two methods always agree.
Open the free Board Foot Calculator →The calculator includes a separate length helper for ordering by the running foot, plus full board-foot math and a project cut list. For the underlying unit, see what a board foot is.