Board Foot vs Linear Foot
The difference between board feet and linear feet, and a converter that does the math.
Linear feet only measure length. To convert to board feet you also need the thickness and width, because board feet measure volume. A board that is 1 in by 6 in gives half a board foot per linear foot; a 2 in by 12 in gives two board feet per linear foot.
The short version
A linear foot measures length only. A board foot measures volume: thickness times width times length. Two boards can be the same linear feet and very different board feet if one is thicker or wider.
When each is used
Trim, molding, and dowels are usually sold by the linear foot, because the profile is fixed and only length varies. Rough hardwood is almost always sold by the board foot, because thickness and width change from board to board and you are really paying for volume.
Converting between them
To turn linear feet into board feet you need the board's thickness and width:
board feet = thickness in x width in x linear feet / 12
A 1x6 gives half a board foot per linear foot. A 2x12 gives two board feet per linear foot, four times as much for the same length. The converter above does it for any profile.
Frequently asked questions
- Is a linear foot the same as a board foot?
- No. A linear foot is just length. A board foot is volume and depends on thickness and width too.
- How do I convert linear feet to board feet?
- Multiply thickness in inches by width in inches by the linear feet, then divide by 12. You cannot convert without knowing the board thickness and width.
- Why is lumber sold both ways?
- Fixed-profile products like molding vary only in length, so linear feet make sense. Rough lumber varies in thickness and width, so board feet price the actual volume.