The most common mistake made in calculating board footage is forgetting to multiply by the thickness. 4/4 multiply by 1, 5/4 multiply by 1.25, 6/4 multiply by 1.5 8/4 multiply by 2, 12/4 multiply by 3, 16/4 multiply by 4 Example 1: A 4/4 board 8 inches wide and 8 feet long has 5.33 bd.ft.

Example 1: A 4/4 board 8 inches wide and 8 feet long has 5.33 bd.ft. 8in x 8ft x 1in = 5.33 bd.ft. - or - 8in x 96in x 1in = 5.33 bd.ft. 12 144 

While hardwoods and softwoods may look somewhat similar in size and shape in stacks at the lumberyard, the method for calculating the cost of each is quite different. Softwoods are dimensional lumber, meaning that they are cut into uniform sizes (2x4, 1x8, etc.). All of the boards of the same size in a stack at the lumberyard are going to be the same price. With hardwoods, the story is quite different. Hardwoods are sold by the board foot, which is a calculation of the cubic size of the board. A board foot is 12 inches by 12 inches by 1 inch, or one-twelfth of a cubic foot.