Board Foot Calculator
Board feet of lumber from thickness, width, and length.
Input sheet
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Hardwood lumber is priced by the board foot, a volume measure that confuses anyone used to buying boards by length. This calculator computes board feet from a board's dimensions and quantity so you can price a stack accurately.
How it works
One board foot is 144 cubic inches: thickness × width (inches) × length (feet) ÷ 12, times the number of boards.
One board foot is 144 cubic inches — the volume of a 1-inch-thick, 12-inch-wide, 1-foot-long board. The calculator multiplies thickness × width (in inches) × length (in feet), divides by 12, then multiplies by the number of boards for the total.
Because it's a volume measure, a thick or wide board is more board feet than a thin or narrow one of the same length — which is exactly how lumber yards price the difference.
Board feet per board = (thickness × width × length) ÷ 12; total = board feet per board × quantity.
Worked examples
Ten 2 in × 6 in × 8 ft boards. → 80 board feet total.
2 × 6 × 8 ÷ 12 = 8 board feet per board × 10 = 80 board feet.
Five 1 in × 8 in × 10 ft hardwood boards. → About 33.3 board feet total.
1 × 8 × 10 ÷ 12 = 6.67 board feet each × 5 ≈ 33.3 board feet.
Tips & gotchas
- Use the rough (nominal) thickness for pricing — hardwood is sold by quarters (4/4 is 1 inch rough), and the board-foot price applies before it's planed down.
- Buy 15–20% extra for woodworking projects to allow for defects, cutting around knots, and matching grain.
- Board feet measure volume, not surface — two boards with the same board-foot count can be very different shapes.
- When comparing lumber prices, always compare per board foot, not per board, since board sizes vary.
FAQ
What exactly is a board foot?
A board foot is 144 cubic inches of lumber — equivalent to a board 1 inch thick, 12 inches wide, and 1 foot long. It measures volume, which is why thickness and width both matter.
Is a board foot the same as a linear foot?
No. A linear foot measures only length; a board foot measures volume, factoring in thickness and width too. A long, thin board can be fewer board feet than a short, thick one.
How much extra lumber should I buy?
Plan on 15–20% over your finished board-foot need for furniture and cabinetry — you'll lose material to defects, knots, cutting around the grain, and final dimensioning.
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