How this instrument works
Lumber is priced and sold by the board foot — a unit of volume equal to a 1×12×12-inch, one square foot, one inch thick, piece of wood — not simply by length or piece count. This calculator computes board feet from a piece's actual cross-sectional area and length, then multiplies by your quantity and a price-per-board-foot figure to estimate total material cost.
The catch with dimensional lumber is that its 'nominal' name, a 2×6 say, isn't its actual size. A rough-sawn 2×6 starts life at roughly 2×6 inches, but planing and drying shrink it to a standard actual dressed size of 1.5×5.5 inches, per the PS-20 American Softwood Lumber Standard the US lumber industry has followed for decades. This calculator's size dropdown already applies those standard actual dimensions, so 'nominal 2×6' correctly computes board feet from the true 1.5×5.5in cross-section, not the misleading 2×6 nominal figure.
Price per board foot is left fully editable because lumber pricing swings constantly and varies enormously by species, grade, treatment, and regional market conditions — framing lumber, cedar, and pressure-treated stock can differ by several times the per-board-foot cost. The 0.85 default here is a rough planning placeholder only; check current pricing at your actual supplier before using this for a real budget.
- Select Nominal lumber size from the dropdown — cross-sections are the real PS-20 actual dressed dimensions, e.g. a 2x6 uses 1.5×5.5in, not the nominal 2×6.
- Enter Length per piece (ft) and Number of pieces.
- Enter Price per board foot ($) — check your actual supplier's current pricing; this varies widely by species, grade, and market.
- Read Total board feet and Estimated total cost ($) — a planning-level material cost estimate.
Worked example — ten 8ft nominal 2×6 boards
Select nominal 2×6 (actual 1.5×5.5in, cross-section 8.25 sq in per PS-20), Length per piece to 8ft, Number of pieces to 10, and Price per board foot to $0.85, a rough planning placeholder. Board feet per piece = (8.25 × 8) ÷ 12 = 5.5; total board feet = 5.5 × 10 = 55; estimated cost = 55 × 0.85 = $46.75.
Swap to nominal 2×12 (actual 1.5×11.25in, cross-section 16.875 sq in) at 6 pieces, 12ft each, and a higher $1.10/board-foot price for a premium grade: board feet per piece = 16.875, total board feet = 101.25, and estimated cost = $111.375 — a much larger board-foot count per piece since the wider board's cross-section dominates the calculation.
Questions
What is a board foot, and why isn't lumber priced by linear foot?
A board foot is a volume measurement equal to a piece of wood 12 inches long, 12 inches wide, and 1 inch thick — 144 cubic inches. Lumber is priced this way, rather than by simple linear length, because boards come in many different widths and thicknesses; a 2×12 obviously contains more wood per linear foot than a 2×4, so pricing by volume rather than length is the only way to compare costs fairly across different board sizes.
Why is a nominal 2×6 actually smaller than 2 inches by 6 inches?
Because nominal size describes the board's rough-sawn dimension before it's planed smooth and dried to a standard moisture content, both of which remove material. The PS-20 American Softwood Lumber Standard, the industry reference the US lumber trade has used for decades, sets the actual finished size at 1.5×5.5 inches for anything sold as a nominal 2×6 — this calculator's dropdown already uses that real dressed size, not the misleading nominal number, so the board-foot math comes out accurate.
Why does board-foot price vary so much between suppliers?
Lumber pricing is driven by species (a construction-grade SPF stud costs far less than clear cedar or hardwood), grade, treatment (pressure-treated costs more than untreated), and regional market swings that can move framing-lumber prices significantly within a single season. Because of that, this calculator's price-per-board-foot input is a rough planning placeholder — always check your actual supplier's current pricing before using this for a real project budget.
Does board footage account for waste, like cuts and trimming?
No — it computes the raw material volume of the pieces exactly as you specify them, with no allowance for cutting waste, defects you'll trim away, or extra pieces for mistakes. If your project involves cutting boards down to shorter final lengths, budget extra board feet, or extra pieces, beyond this calculator's raw total to cover that waste, similar to how a waste percentage is applied in coverage-based material calculators.
Can I use this for hardwood, not just softwood framing lumber?
The board-foot math works for any species, but the Nominal lumber size dropdown here lists the nine common PS-20 dressed sizes for standard softwood dimensional lumber, like 2x4 through 2x12 and 4x4 posts. Hardwood is often sold by different conventions, such as rough-sawn thickness in quarters (4/4, 5/4, 8/4) rather than nominal softwood dimensions, so if your hardwood board's actual cross-section doesn't match a listed size, compute board feet by hand with this same formula: cross-section (sq in) × length (ft) ÷ 12.