What is Board Foot?
A board foot is a unit of volume for hardwood lumber equal to 144 cubic inches, or a piece 12 inches long, 12 inches wide, and 1 inch thick.
A board foot (BF) is the standard unit for buying and selling hardwood lumber in North America. One board foot equals 144 cubic inches of wood, or a piece measuring 12 x 12 x 1 inches.
The formula. Thickness (inches) x Width (inches) x Length (inches) / 144 = board feet. For a board measured in feet: Thickness (inches) x Width (inches) x Length (feet) / 12.
Quick examples: - A 1 x 6 x 8 ft board = 1 x 6 x 8 / 12 = 4 board feet - A 2 x 4 x 10 ft board = 2 x 4 x 10 / 12 = 6.67 board feet - A 4/4 x 8 inch x 6 ft walnut board = 1 x 8 x 6 / 12 = 4 board feet
Quarter system. Hardwood thickness uses quarter-inch notation: 4/4 = 1 inch, 5/4 = 1.25 inches, 6/4 = 1.5 inches, 8/4 = 2 inches. These are rough-sawn thicknesses before surfacing. A 4/4 board planes down to about 13/16 inch.
Board feet vs. linear feet. Softwood (pine, spruce, cedar) sells by the linear foot at a set price per piece. Hardwood (oak, maple, walnut) sells by the board foot because widths vary from board to board. A wider board costs more because it contains more wood.
Pricing. Hardwood prices range from $3-6/BF for red oak and poplar to $12-25/BF for walnut, cherry, and figured maple. Exotic species can exceed $40/BF.
In the cut list workflow, converting your parts list to board feet tells you exactly how much lumber to purchase. SmartCutList calculates board footage from your part dimensions, accounting for rough-cut allowances and waste.
Frequently Asked Questions
- How do you calculate board feet?
- Multiply thickness (inches) x width (inches) x length (feet), then divide by 12. For example, a 1-inch-thick, 6-inch-wide, 8-foot-long board equals 1 x 6 x 8 / 12 = 4 board feet. For thickness in quarter notation, 4/4 equals 1 inch, 8/4 equals 2 inches.
- How much does a board foot of walnut cost?
- Black walnut ranges from $8-15 per board foot for FAS grade (clear, wide boards) at retail lumber yards. Figured walnut with curly or crotch grain can cost $20-40+ per board foot. Prices vary by region, supplier, and current demand. Buying rough-sawn directly from sawmills saves 20-40%.
- What is the difference between a board foot and a linear foot?
- A board foot measures volume (12 x 12 x 1 inches of wood). A linear foot measures only length, regardless of width or thickness. Hardwood is sold by the board foot because widths vary from board to board. Softwood and molding are sold by the linear foot at a fixed price per piece.
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