Board Foot Calculator
Calculate lumber volume from thickness, width, length and quantity, with optional price per board foot.
Continue your project estimate
Plan deck-board layout for a deck project →Board foot formula
A board foot is 144 cubic inches. With thickness and width in inches and length in feet, board feet equal thickness × width × length ÷ 12.
Board feet vs. linear feet
Linear feet measure length only. Board feet also account for thickness and width, which makes them useful for lumber volume and supplier pricing.
Nominal size versus the dimensions you enter
Board-foot volume is based on the dimensions entered into the formula. Lumber can be described by nominal trade sizes while the actual dressed dimensions are smaller, so use the measurement basis that matches the way your supplier quotes or prices the material.
If a supplier prices rough lumber by board foot, use the thickness, width and length basis they specify. If the project is being planned from finished dimensions, keep that distinction visible instead of assuming every “2 × 4” has the same volume basis.
Common board-foot examples
These quick checks use the stated thickness and width as the calculation dimensions and an 8 ft length. They are arithmetic references, not a claim that nominal dressed lumber has those exact physical dimensions.
| Size basis | Length | Board feet |
|---|---|---|
| 1 × 4 | 8 ft | 2.67 BF |
| 1 × 6 | 8 ft | 4 BF |
| 1 × 8 | 8 ft | 5.33 BF |
| 1 × 10 | 8 ft | 6.67 BF |
| 1 × 12 | 8 ft | 8 BF |
| 2 × 4 | 8 ft | 5.33 BF |
For purchasing, use the dimension basis your mill or supplier uses for board-foot pricing. Enter the exact values in the calculator above when your stock differs.
Board-foot cost example
Ten boards that are 1 inch thick, 8 inches wide and 8 feet long equal about 53.33 board feet. At an entered price of $4 per board foot, the material estimate is about $213.33 before taxes, delivery, waste or project-specific extras.
The optional price field is useful for comparing supplier quotes, but it does not replace a project takeoff. A deck, wall or cabinet project may require extra pieces because of lengths, defects, cut layout or species/grade requirements.
Use board feet with the right project calculator
Board feet measure lumber volume. They do not determine stud spacing, deck-board layout, sheet goods or structural sizing. Use the Stud Calculator for wall framing quantities, the Deck Board Calculator for decking surface rows and linear footage, and the Plywood Calculator for sheet material.
For the wider estimating workflow, use the Construction Estimating Formulas reference, then collect separate material and cost estimates in the Project Budget Workspace.
Related calculators
Compare dimensions before ordering rough lumber
For ten boards 8 ft long and 8 inches wide, a 1-inch thickness corresponds to 10 × (1 × 8 × 8 ÷ 12) = 53.33 board feet. If the quoted thickness is 1.5 inches instead, the same number and face size of boards correspond to 80 board feet. At an illustrative supplier rate of $4 per board foot, those quantities cost about $213.33 and $320 respectively, excluding transport and other work.
Ask the seller whether pricing is based on nominal, rough-sawn or finished actual dimensions. The entered volume is not automatically the invoiced board-foot volume if the supplier uses a different measurement convention. Species, grade, defects and usable lengths can also affect what is suitable to buy.