Board Foot Calculator
A board foot is the standard unit of measure for hardwood lumber in the United States, equal to 144 cubic inches (a 1-inch-thick, 12-inch-wide, 12-inch-long piece). The formula is: BF = (Thickness in inches x Width in inches x Length in feet) / 12. Lumber dealers price hardwood by the board foot. This calculator also applies to rough-sawn lumber where boards vary in width. Enter dimensions per board and quantity; the tool calculates total board feet for the full order.
Board foot formula
Board Feet = Thickness (in) x Width (in) x Length (ft) / 12
Total Board Feet = Board Feet per board x Quantity
One board foot = 144 cubic inches = 1/12 cubic foot. The formula can also be expressed as: BF = T(in) x W(in) x L(in) / 144, where all measurements are in inches. Hardwood dealers often quote length in feet and thickness in inches using the /12 formula.
Common hardwood lumber sizes
- 4/4 (1 inch thick, actual approximately 13/16 inch surfaced): most common hardwood thickness.
- 5/4 (1.25 inches): used for tabletops and wider furniture components.
- 6/4 (1.5 inches): used for chair legs and structural furniture parts.
- 8/4 (2 inches): used for heavy furniture, cutting boards, and turning blanks.
- Widths in hardwood vary naturally; random-width lumber is common and priced per board foot.
Board foot calculator: frequently asked questions
What is a board foot of lumber?
A board foot is a unit of lumber volume equal to a piece that is 1 inch thick, 12 inches wide, and 12 inches long (1/12 of a cubic foot). It is the standard unit for pricing and measuring hardwood lumber in the United States.
How do I calculate board feet?
Board Feet = (Thickness in inches x Width in inches x Length in feet) / 12. For example, a 2-inch thick, 6-inch wide, 10-foot long board = (2 x 6 x 10) / 12 = 10 board feet.
Are board feet used for softwood dimensional lumber?
Softwood lumber (2x4, 2x6, etc.) is usually sold by the lineal foot or piece, not board feet. Board feet are primarily used for hardwood lumber sold at sawmills and hardwood lumber dealers, where boards vary in width and thickness.
What are nominal vs actual lumber dimensions?
Nominal dimensions (2x4, 2x6, etc.) are the size before drying and surfacing. Actual dimensions are smaller: a 2x4 is actually 1.5 inches x 3.5 inches. Board feet for hardwood are calculated using the actual (rough) dimensions at the sawmill.
How do I calculate total board feet for multiple boards?
Calculate board feet per board and multiply by the number of boards. This calculator includes a quantity field. Total BF = (T x W x L / 12) x Quantity.
Official sources
- USDA Forest Products Laboratory: FPL-GTR-282 Wood Handbook (2021 Edition).
- National Hardwood Lumber Association: NHLA Rules for the Measurement and Inspection of Hardwood and Cypress Lumber.
Reviewed by the CalculatorHub team, edited by James Graham, 15 June 2026. See our methodology.