How this calculator works
A board foot is a volume, not an area: it is one square foot of board one inch thick, which is 144 cubic inches. Take thickness in inches, width in inches and length in feet, multiply them and divide by 12. Hardwood is priced this way because the nominal rough thickness and the board width both change what a stick of lumber contains, and a batch simply multiplies the single-board figure.
Formula
Board feet = thickness (in) × width (in) × length (ft) ÷ 12, times the number of boards. One board foot is 144 in³ or 0.002359737216 m³.
Worked example
A 2 in thick, 6 in wide, 10 ft board is 2 × 6 × 10 ÷ 12 = 10.0 board feet. Twenty boards at 1 in thick, 8 in wide and 12 ft long come to 160 board feet, which is 0.378 m³.
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Frequently asked questions
Do I use nominal or actual thickness?
For rough hardwood, use the nominal quarter measure: 4/4 is entered as 1 in. For dressed softwood the board shrinks, so a 2 by 4 is really 1 1/2 by 3 1/2 in and a lumberyard prices it as a dimensional size, not by board feet.
Why is board feet used in Canada?
Hardwood imported and sold in Canada is often still quoted in board feet, while domestic dimension lumber and exports are quoted in cubic metres. Both outputs are shown so a quote in either unit can be checked.
Is a board foot the same as a linear foot?
No. A linear foot measures length only, which is how decking and trim are sold. A board foot also includes width and thickness, which is how hardwood is sold.