Board Feet Calculator
Calculates the total board feet of lumber needed for a woodworking project, including a waste factor. Use it when buying timber at the lumber yard or estimating material costs.
About this calculator
A board foot is a unit of lumber volume equal to a piece 12 inches long, 12 inches wide, and 1 inch thick — effectively 144 cubic inches. The formula is: boardFeet = ((length × width × thickness × quantity) / 144) × wasteFactor. Dividing by 144 converts cubic inches into board feet. The waste factor (e.g., 1.10 for 10% waste) accounts for off-cuts, defects, and planning errors that always consume extra material. Lumber yards price wood by the board foot, so knowing your total before you shop prevents costly shortfalls or over-purchasing. Hardwoods are almost always sold this way, making this calculation essential for furniture makers and finish carpenters alike.
How to use
Suppose you need 6 oak boards, each 96 inches long, 6 inches wide, and 1 inch thick, with a 10% waste factor (1.10). boardFeet = ((96 × 6 × 1 × 6) / 144) × 1.10 = (3,456 / 144) × 1.10 = 24 × 1.10 = 26.4 board feet You would order at least 26.4 board feet of oak. At a typical price of $8/BF, that works out to roughly $211 before tax.
Frequently asked questions
How do I calculate board feet for lumber with odd dimensions?
Simply plug the actual measured dimensions in inches into the formula: (length × width × thickness × quantity) / 144. If a board is 84 inches long, 5.5 inches wide, and 0.75 inches thick, you still use those exact numbers. The result is accurate regardless of whether the dimensions are standard or non-standard. Always measure actual (dressed) dimensions, not nominal ones, since a '1×6' board is typically only 0.75 × 5.5 inches after milling.
What waste factor should I use for a woodworking project?
A 10% waste factor (1.10) is standard for straightforward projects with clean, defect-free lumber. Increase it to 15–20% (1.15–1.20) when working with figured or knotty wood that requires selective cutting. For diagonal or herringbone patterns, a 25% factor (1.25) is common because angled cuts waste the corners of each board. Projects involving beginner-level joinery or hand tools also benefit from a higher factor to account for learning mistakes.
Why is lumber measured in board feet instead of linear feet?
Board feet capture three dimensions — length, width, and thickness — in a single volume-based unit, making price comparisons fair across boards of different sizes. Linear feet only measure length, so a wide, thick plank would appear the same 'size' as a narrow strip, which would be misleading for pricing. The board foot standard lets both buyer and seller agree on a consistent measure of wood volume regardless of the specific cut. This is especially important in hardwood markets where boards vary widely in width and thickness.