How this calculator works
One board foot is the volume of a board 1 inch thick, 12 inches wide and 1 foot long: 144 cubic inches. For any board, multiply thickness (in) by width (in) by length (ft), then divide by 12.
Worked example: ten boards that are 1 in thick, 6 in wide and 8 ft long hold 1 × 6 × 8 ÷ 12 = 4 board feet each, so 40 board feet in all. At $4 per board foot that is $160.
Tips before you buy
- Lumber is sold by its nominal size, not its actual size. A 2×4 is really 1½ × 3½ in. Hardwood is usually measured in quarters, so 4/4 (four-quarter) is 1 in thick before it is planed.
- Buy 15 to 25% more than your cut list. Hardwood has knots, checks and crook, and milling takes material off.
- Board feet are for pricing hardwood by volume. For a project, add up the parts you need and the waste to get what to buy.
Tools & materials for this project
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Frequently asked questions
How do you calculate board feet?
Thickness in inches × width in inches × length in feet, divided by 12. A 2 × 6 that is 8 ft long is 2 × 6 × 8 ÷ 12 = 8 board feet (using the nominal size).
How many board feet are in a 2x4?
A 2×4 that is 8 ft long is 5.33 board feet by nominal size (2 × 4 × 8 ÷ 12), though its actual dimensions are smaller.
Why is hardwood sold by the board foot?
Because hardwood boards come in random widths and lengths. Pricing by volume is fairer than pricing per piece.
Related calculators & guides
Estimates only. Results assume standard materials and simple shapes. Supplier products vary, and the final call on quantity, structure and safety is yours. Check your local code and your supplier's guidance before ordering.