Calculating board feet is quick once you keep your units straight. A board foot is 144 cubic inches of lumber, so the whole job is measuring a board's volume in cubic inches and dividing by 144. The single most common mistake is mixing feet and inches — so we will handle that first.
The formula needs every dimension in inches. Take a board 1″ × 6″ × 8 ft. Convert the length first: 8 ft × 12 = 96 in. Then (1 × 6 × 96) ÷ 144 = 576 ÷ 144 = 4.00 board feet. If you forgot to convert and used 8 instead of 96, you would get 0.33 bf — twelve times too small. Always convert feet to inches before multiplying.
For several copies of the same board, calculate one and multiply by the count. Five boards of 4/4 × 8″ × 10 ft:
| Step | Value |
|---|---|
| Length to inches | 10 ft × 12 = 120 in |
| One board | (1 × 8 × 120) ÷ 144 = 6.667 bf |
| Times quantity 5 | 6.667 × 5 = 33.33 bf |
For a project with different parts, calculate each part separately and add the board-foot totals together — that is exactly what a cut list does.
Multiply total board feet by the yard's price per board foot. At $6.50/bf, those 33.33 board feet come to about $216.67. Many yards round each board up to the next quarter-foot, so treat your number as a close estimate.
Open the free Board Foot Calculator →The calculator handles the feet-to-inches conversion for you, supports metric input, and lets you total an entire project with a cut list. For the underlying idea, see what a board foot is.