“Board Feet” Is a measurement of lumber volume. A board foot is equal to 144 cubic inches of wood. You can calculate the board footage using this formula in inches.
(Thickness × Width × Length) / 144 = Board Feet
Note: Lumber is specified by its rough size. This is why a 1” × 4” board is actually 3⁄4” thick and a 2” × 4” board is actually 1 1⁄2” thick.
Once you have your board feet calculated, keep wasted material in mind. If you purchase good clear material add about 15% for waste. If you elect to use lower grade material you will have to allow for defects and more wasted material. Add about 30%.