What Is a Board Foot?
A clear definition of board-foot volume with dimensional examples.
A board foot is 144 cubic inches
A board foot is a unit of lumber volume, not a required board shape. The familiar reference piece is 1 inch thick, 12 inches wide and 12 inches long. It contains 144 cubic inches. Any other combination of dimensions containing the same volume also equals one board foot.
Because the unit includes thickness, width and length, it differs from a linear foot and a square foot. Saying that a board is eight feet long does not reveal its BF; saying that a surface covers eight square feet still omits thickness.
Different shapes, equal volume
A 2-inch by 6-inch board one foot long is one board foot. So is a 0.75-inch layer covering 1⅓ square feet. An eight-foot board measuring 1 × 6 inches contains 4 BF because 1 × 6 × 8 ÷ 12 equals 4. The unit lets differently shaped boards be compared by volume.
How board feet is used
Hardwood sellers commonly use board-foot tallies to describe volume, while softwood retail products may be priced by piece or linear foot. A board-foot figure does not communicate species, grade, moisture, surfacing, defects or finished yield. Those facts remain separate parts of a purchase specification.
Reading a BF figure critically
Ask which dimensions were used, whether they were actual or nominal, how widths and lengths were rounded, and whether an allowance was added. For a mixed pile, keep each size visible. For a log, a board-foot scale is an estimated yield under a named rule, not the same measurement as sawn-board volume.
Questions about this topic
Is a board foot a 12-inch-long board?
No. It is volume; many shapes can equal 144 cubic inches.
Can thin lumber have board feet?
Yes. Thickness is multiplied just like width and length.
Does BF tell me how many boards I receive?
No. Board count depends on the dimensions of each piece.
Related BoardFoot Bench pages
Method and content reviewed 3 September 2026.