What is a board foot?
A board foot (BF) is the standard unit used to measure and price hardwood and rough-sawn lumber in North America. One board foot equals a volume of 144 cubic inches — for example a piece 12 inches long, 12 inches wide and 1 inch thick. Because lumber is bought by volume rather than by surface area, the board foot lets buyers compare boards of different sizes on equal terms.
How to use this calculator
Enter the length, width and thickness of one board, all measured in inches. Then enter how many identical boards you have. The calculator returns the board feet of a single board and the total board feet for the whole batch, so you can estimate cost and quantity quickly.
The formula explained
The core equation is $$\text{BF} = \frac{L \times W \times T}{144}$$ where every dimension is in inches. The divisor 144 converts cubic inches into board feet (since \(12 \times 12 \times 1 = 144\)). To get the total for several boards, multiply the per-board result by the number of boards: $$\text{BF}_{\text{total}} = \text{BF} \times N$$
Worked example
Suppose you have 5 boards, each 96 inches long, 6 inches wide and 1 inch thick. Per board: $$\frac{96 \times 6 \times 1}{144} = \frac{576}{144} = 4 \text{ board feet}$$ For 5 boards: \(4 \times 5 = 20\) board feet total.
FAQ
Does the length have to be in inches? This calculator expects all three dimensions in inches. If your length is in feet, multiply it by 12 first.
Should I use rough or finished thickness? Lumber is usually priced on its rough (nominal) thickness before surfacing, so use the rough thickness when estimating cost.
How is total cost found? Multiply the total board feet by the price per board foot quoted by your supplier.
