Lumber / Board Feet Calculator
Calculate board feet of lumber needed from dimensions and piece count.
Assumptions used in this calculation
- Nominal dimensions: Uses the nominal lumber size you enter (e.g. a '2×6'), actual dressed/finished lumber is typically smaller (a nominal 2×6 is actually about 1.5×5.5 inches), which matters for structural calculations but not for pricing, since lumber is sold by nominal size.
- No cutting waste: Doesn't add any allowance for kerf loss or waste from cutting boards to final length.
About this calculator
Lumber isn't priced by the piece or even by linear length the way you might expect, it's priced by the board foot, a volume unit equal to a 1×12×12-inch piece, which means comparing quotes or ordering the right quantity requires converting your actual piece dimensions and count into that unit first. This calculator multiplies thickness in inches by width in inches by length in feet, divides by 12 to convert into board feet per piece, then multiplies by the number of pieces to get total board feet across your whole order. Enter thickness, width, length and piece count, and it returns the figure lumber yards actually quote against, instead of you working through the unit conversion by hand for every different board size in a project. It uses the nominal size you enter (like a '2×6'), which is what lumber is priced and sold by, even though the actual dressed, finished dimensions of that same board run slightly smaller.
Worked example
2in × 6in × 8ft boards, 20 pieces
Result: 160 board feet
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