Board Foot Calculator
Calculate board feet of lumber from the thickness, width and length, times the number of pieces — with an optional price per board foot for the total cost.
How to calculate board feet
A board foot is a unit of lumber volume — the amount of wood in a piece 1 inch thick, 12 inches wide and 1 foot long. Hardwood is priced by the board foot, so knowing the total tells you what a project will cost. Enter the thickness and width in inches and the length in feet, set how many pieces you have, and the calculator returns the board feet (and the cost if you add a price).
board feet = thickness (in) × width (in) × length (ft) ÷ 12
For example, a 2-inch by 6-inch board that is 8 feet long is 2 × 6 × 8 ÷ 12 = 8 board feet. A “2×4×8” works out to 2 × 4 × 8 ÷ 12 = 5.33 board feet. Use the nominal size for pricing, since dressed lumber (a “2×4” is really about 1.5 × 3.5 in) is still sold by its nominal dimensions.
Board feet of common boards
| Board (nominal) | Board feet |
|---|---|
| 1×4 × 8 ft | 2.67 bd ft |
| 2×4 × 8 ft | 5.33 bd ft |
| 2×6 × 8 ft | 8 bd ft |
| 4×4 × 8 ft | 10.67 bd ft |
Board feet measure volume, not length — two boards of the same length differ if their thickness or width differs. For sheet goods or volume in cubic units instead, see the cubic feet calculator.
Frequently asked questions
How do I calculate a board foot?
A board foot is the volume of a piece 1 inch thick, 12 inches wide and 1 foot long. The formula is thickness (in) × width (in) × length (ft) ÷ 12. Multiply by the number of pieces for the total. The calculator does this for any dimensions you enter.
How many board feet is a 2x4x8?
A 2×4 that is 8 feet long is 2 × 4 × 8 ÷ 12 = 5.33 board feet. Note that nominal “2×4” lumber actually measures about 1.5 × 3.5 inches once dressed — use the nominal size for pricing, as that is how lumber is sold.
What is the difference between a board foot and a linear foot?
A linear foot measures length only; a board foot measures volume (thickness × width × length). Two boards of the same length can have very different board-foot totals if their thickness or width differs, which is why hardwood is priced by the board foot.