What is the difference between a board foot and a linear foot?
A linear foot is a foot of length. A board foot is 144 cubic inches of wood. One 2x6 foot is one linear foot and one board foot — and for every other size they differ.
A linear foot measures length only; a board foot measures volume — 144 cubic inches, or a piece 12" × 12" × 1".
They coincide exactly on a 2x6: one foot of it is 1.0 board foot. Everything narrower gives less than a board foot per linear foot, everything wider gives more.
How that is worked out
- A linear foot is twelve inches of board, whatever its width or thickness. It is how trim, molding and dimensional softwood are usually priced.
- A board foot is length × width × thickness in inches ÷ 144. It measures wood, not length, which is why hardwood is sold in it — a wide thin board and a narrow thick one cost the same if they contain the same material.
- Per linear foot, the board feet in a piece are just width × thickness ÷ 12. A 2x6 gives 1.0; a 1x4 gives 0.33; a 2x12 gives 2.0.
Board feet contained in one linear foot, by nominal size
| Nominal size | Board feet per linear foot | Linear feet per board foot | One 8' stick |
|---|---|---|---|
| 1x4 | 0.333 | 3.00 | 2.67 bf |
| 1x6 | 0.500 | 2.00 | 4.00 bf |
| 1x8 | 0.667 | 1.50 | 5.33 bf |
| 2x4 | 0.667 | 1.50 | 5.33 bf |
| 2x6 | 1.000 | 1.00 | 8.00 bf |
| 2x8 | 1.333 | 0.75 | 10.67 bf |
| 2x10 | 1.667 | 0.60 | 13.33 bf |
| 2x12 | 2.000 | 0.50 | 16.00 bf |
Worth knowing
- Softwood by the nominal size is counted on the name, not the dressed size. That is how the yard invoices it, and it is why a 2x4 is 5.33 bf per eight-foot stick rather than the 3.5 the actual dimensions give.
- Hardwood is measured rough, before it was dressed, so the board foot you pay for is the wood as the mill cut it. You are buying the sawdust too, and always have been.
- MBF — thousand board feet — is how mill quotes and lumber futures are written. Converting a per-piece price into MBF is the way to tell whether the yard's price is reasonable.
- Trim and molding are sold by the linear foot because their profile, not their volume, is what you are buying. Nobody quotes crown in board feet.
Work out your own numbers
- Board foot calculator
How much lumber to buy for a finished piece, what it will cost, and what to ask for at the yard.
- Board cut calculator
How many pieces of one length come out of a board of another, with the kerf charged between cuts and the leftover shown.
Related questions
- Is a board foot the same as a linear foot?
- Only for a 2x6, and that is a coincidence of the arithmetic — 2 × 6 ÷ 12 = 1. For anything else they differ: a linear foot of 1x4 is a third of a board foot, and a linear foot of 2x12 is two board feet. One measures length, the other measures wood.
- How do I convert linear feet to board feet?
- Multiply the linear feet by the nominal width and thickness in inches, then divide by 12. Sixteen linear feet of 2x8 is 16 × 8 × 2 ÷ 12 = 21.3 board feet. The divisor is 12 rather than 144 because you are already working in feet of length.
- Why is hardwood sold by the board foot?
- Because hardwood comes in random widths. Softwood arrives as 2x4s and 2x6s, so a price per piece or per linear foot works. A stack of hardwood is whatever widths the log gave, so the only fair way to price it is by how much wood is in it — which is what a board foot measures.