How to Calculate Board Feet
A board foot is the standard unit for measuring and pricing hardwood lumber. One board foot equals 144 cubic inches — the volume of a board 1 foot long, 1 foot wide, and 1 inch thick. Knowing how to calculate board feet lets you estimate material cost and quantity before you cut.
The board-foot formula
Board feet = (thickness in inches × width in inches × length in inches) ÷ 144. If the length is in feet, multiply thickness × width in inches by length in feet, then divide by 12 instead.
Worked example
A board 1 inch thick, 6 inches wide, and 8 feet long: (1 × 6 × 96) ÷ 144 = 4 board feet. The same board calculated with the feet formula: (1 × 6 × 8) ÷ 12 = 4 board feet. Both give the same answer.
Board feet vs. linear feet
Linear feet measure only length, ignoring width and thickness. Board feet measure volume, so a wider or thicker board contains more board feet per linear foot. Hardwood is usually sold by the board foot; dimensional softwood and trim are often sold by the linear foot.
Why it matters for cutting
Board feet tell you how much raw material a project needs and what it will cost. Combine that estimate with linear cutting optimization to decide how many boards to buy and how to cut them with the least waste.
Frequently asked questions
Does board foot account for waste?
No. Board feet measure finished board volume only. Add a waste allowance — often 15–30% for hardwood — to cover defects, kerf, and offcuts.
How do I calculate board feet for rough lumber?
Use the rough (nominal) thickness, such as 4/4 for one inch, since hardwood is priced on rough dimensions before surfacing.
Put this into practice
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