Lumber Calculator

Multiply the nominal thickness in inches by the nominal width in inches by the length in feet, then divide by 12. A 2x10x12 is 2 × 10 × 12 ÷ 12 = 20 board feet. Multiply by the number of pieces for the order total. If the order mixes sizes, work out each size separately and add them.

Multiply board feet by the price per board foot, size by size, and add them up. 40 2x4x8 studs are 213.33 bd ft and 12 2x10x12 joists are 240 bd ft. At $1.00 and $1.20 per board foot that is $213.33 plus $288.00, or $501.33. Those rates only illustrate the arithmetic. Enter your supplier's prices in the calculator.

Divide the piece price by the board feet in one piece. A 2x4x8 is 5.33 bd ft, so a $4.00 stud works out to $0.75 per board foot. A quote per MBF (1,000 board feet) divides by 1,000: $750 per MBF is $0.75 per board foot. Set the price unit to per piece in the calculator and it shows the cost per board foot.

One board foot is a piece 12 inches long, 12 inches wide, and 1 inch thick, or 144 cubic inches. It measures volume, not length, which is where people often get confused. Lumber yards price hardwood and larger dimensional orders this way because it puts a 1x8 and a 2x4 on the same terms.

Nominal, the size printed on the tag. A 2x6 actually measures 1.5 by 5.5 inches once it's been dressed, but board footage and pricing both run off the nominal 2x6. If you use the actual dressed size, your total will come out well short.

Linear footage measures length only and ignores width and thickness, so it works only for one fixed board size (as in "how many linear feet of 2x4 do I need"). Board footage measures volume, so you can use it to compare or price different lumber sizes against each other.

5.33 board feet: 2 in thick times 4 in wide times 8 ft long, divided by 12. A 1x6x8 works out to 4 board feet the same way. For a full order, multiply one piece by the quantity, and add a size line in the calculator for each other board size.