How this calculator works
A board foot is a unit of lumber volume equal to 12 × 12 × 1 inch. The formula is simple: thickness (in) × width (in) × length (ft) ÷ 12 — then multiply by the number of boards.
Worked example — 10 boards at 1 in × 6 in × 8 ft:
(1 × 6 × 8) ÷ 12 = 4 board feet each × 10 = 40 board feet.
(1 × 6 × 8) ÷ 12 = 4 board feet each × 10 = 40 board feet.
When board feet matter
Softwood framing lumber is typically priced by the linear foot or per piece, but hardwood (oak, maple, walnut) is almost always priced by the board foot. Knowing your total makes it easy to compare prices at the lumber yard.
Frequently asked questions
What is a board foot of lumber?
One board foot equals 144 cubic inches — the volume of a piece 1 inch thick, 12 inches wide, and 1 foot long.
How do I calculate board feet?
Multiply thickness (inches) × width (inches) × length (feet), then divide by 12.