Board Foot Calculator
Length, width, thickness, and piece count in — board feet out, per piece and for the whole order, with a cost line at whatever price per board foot your supplier quotes. The formula is the industry's own: length (ft) × width (in) × thickness (in) ÷ 12.
Piece dimensions and count
Example: 10 pieces, 8 ft long at 3.5 × 1.5 in → 35 board feet.
Quantity estimates only — board-foot totals say nothing about structural adequacy, span capacity, code compliance, or engineering. Verify dimensions, grades, and local code with a professional.
The board-foot formula, worked
One board foot is a 12 × 12 × 1 in slab of wood — 144 cubic inches. The definition anchor: an 8 ft board, 6 in wide and 1 in thick, is 8 × 6 × 1 ÷ 12 = 4 board feet exactly. The order example uses actual surfaced 2×4 dimensions: 8 ft × 3.5 in × 1.5 in ÷ 12 = 3.5 board feet per piece, so 10 pieces total 35 board feet — at $4.50 per board foot, $157.5. Every figure on this page is computed by the same engine the form calls.
Nominal sizing matters when comparing quotes: a surfaced softwood "2×4" measures about 1 1/2 × 3 1/2 in, so its actual volume is 3.5 board feet per 8 ft stick, not the 5.333 the nominal numbers suggest. Hardwood dealers quote from their own (rough/quarters) sizing — match the convention your supplier uses.
Frequently asked questions
What exactly is a board foot?
A volume unit for lumber: one foot of length by one foot of width by one inch of thickness — 144 cubic inches. The working formula is length in feet × width in inches × thickness in inches ÷ 12. An 8 ft board 6 in wide and 1 in thick is exactly 4 board feet.
Do I enter nominal or actual dimensions?
The tool computes whatever you give it. Hardwood dealers price rough lumber by board feet from nominal (quarters) sizing, while a surfaced softwood 2×4 actually measures about 1 1/2 × 3 1/2 in. If you are pricing against a dealer quote, use the sizing convention the dealer uses; if you are checking real volume, use actual dimensions.
How is this different from linear feet?
Linear feet measure length only and ignore the cross-section; board feet multiply the cross-section in. Trim and framing are commonly sold by the piece or linear foot, while hardwoods and custom milling are quoted per board foot — this tool converts your cut list into that quoting unit.
Can I total different board sizes in one order?
Run each size separately and add the totals — the Feet & Inches Calculator chains the additions if you are also totaling lengths. Each run multiplies one cross-section by one length and piece count, which mirrors how mills tally an order.
Where does the cost figure come from?
Total board feet times the price per board foot you enter — nothing is looked up or assumed. Lumber prices move constantly and vary by species, grade, and region, so the tool only prices from your number.
Related tools: the Flooring Calculator plans the boards that cover a floor, the Stair Calculator lays out the stringers this lumber becomes, and the Feet & Inches Calculator chains cut-list lengths exactly. The Construction Unit Converter covers any other unit move, and the Deck Material Calculator counts the joists and deck boards whose volume this tool prices.
Lumber figures are computed locally and never transmitted. Formula sources and the shared pipeline are documented on the methodology page.