Lumber Board Feet Calculator
Enter a board's thickness, width, and length to calculate board feet (FBM) per board, total board feet, and total lumber cost for any quantity.
Board feet per board
5.33 bf
Total board feet
53.33 bf
Total cost
$266.67
A board foot (FBM, "foot board measure") is a volume unit equal to a 1-inch-thick, 12-inch-wide, 1-foot-long piece of lumber — it's a volume, not a length, which is why a thicker or wider board costs more per foot of length even at the same price per board foot. Use the board's actual (not nominal) dimensions for an accurate result — a "2×4" is typically closer to 1.5 by 3.5 inches once dried and planed.
About this tool
How to use it
- Enter the board's thickness and width in inches, and its length in feet.
- Enter how many boards you're buying, and the price per board foot your supplier quotes.
- Press Calculate Board Feet, or just keep typing — the results update live.
- Use the actual measured dimensions rather than the nominal size printed on the board for the most accurate result.
Why it matters
Lumber is priced by volume, not by the piece or by length alone, so a wider or thicker board costs more even at the same length and the same price per board foot. Converting a stack of boards with specific dimensions into a total cost by hand means multiplying and dividing several numbers correctly in the right order — easy to get wrong, especially at bulk quantities.
When to use it
Useful when pricing out lumber for a project before buying, when comparing quotes from different suppliers who list different unit prices, or when checking that an invoice's board-foot total matches what you actually ordered.
Good to know
A board foot (FBM, 'foot board measure') is a volume unit equal to a 1-inch-thick, 12-inch-wide, 1-foot-long piece of lumber — it measures volume, not length, which is why board feet don't scale linearly with just one dimension. Nominal lumber sizes (like a '2×4') are almost always larger than the board's actual dried and planed dimensions (a '2×4' is typically closer to 1.5 by 3.5 inches) — using the actual dimensions gives a more accurate board-foot count than using the nominal size printed on the label.
Common questions
What is a board foot?
A board foot (FBM) is a unit of lumber volume equal to a board 1 inch thick, 12 inches wide, and 1 foot long — 144 cubic inches. It's how hardwood and most rough lumber is priced, as opposed to dimensional softwood, which is often sold per linear foot instead.
Why does board footage matter more than just length?
Because it's a volume measurement, a thicker or wider board contains more wood — and costs more — even at the identical length. Two boards of the same length can have very different board-foot totals if their thickness or width differs.
Should I use nominal or actual lumber dimensions?
Actual dimensions give the more accurate board-foot count. Nominal sizes (like '2×4' or '1×6') describe the rough-cut size before the wood is dried and planed smooth, which shrinks it — a '2×4' is typically closer to 1.5 by 3.5 inches once finished. Hardwood is more often sold and priced by its actual thickness (in quarters, like '4/4' for 1 inch) rather than a nominal label at all.
Does this account for waste from cutting or defects?
No — this calculates the raw board-foot volume and cost of the lumber as purchased. Real projects typically need extra material to account for cutting waste, knots, and other defects, which isn't factored in here.