Board Foot

A board foot is the standard unit of volume used in the United States lumber industry to measure and price wood. One board foot equals a piece of lumber 12 inches long, 12 inches wide, and 1 inch thick, which works out to 144 cubic inches of wood regardless of the actual shape of the board being measured. Unlike a linear foot, which only tracks length, a board foot accounts for length, width, and thickness together, making it a true volume measurement.

Board feet matter for anyone estimating lumber costs because sawmills and lumberyards typically price hardwood and specialty lumber per board foot rather than per piece. This lets buyers compare a wide 1-inch-thick board against a narrower 2-inch-thick board on equal terms, since both are converted to the same volume-based unit before pricing. The Board Foot Calculator takes a board's length, width, and thickness and converts them into a board foot total, then multiplies by a price per board foot to give a total material cost.

For framing lumber like 2x4s and 2x6s, board feet are less commonly quoted directly to consumers but are still used by suppliers internally to calculate raw material yield and pricing. When estimating volumes for larger material quantities such as bulk fill or concrete, a related but distinct unit is the Cubic Yard, which measures volume for materials sold in bulk rather than by individual board dimensions.

The board foot formula is:

Board Feet = (Thickness in inches × Width in inches × Length in feet) ÷ 12

Where:

• Thickness = board thickness, in inches
• Width = board width, in inches
• Length = board length, in feet
• 12 = converts the result from cubic inches per foot to board feet

If length is also in inches, divide the full product by 144 instead of 12.

Suppose you are buying a hardwood board that is 2 inches thick, 6 inches wide, and 8 feet long.

Board Feet = (2 × 6 × 8) ÷ 12 = 96 ÷ 12 = 8 board feet

If the lumberyard charges $9 per board foot for this hardwood, the total cost would be 8 × $9 = $72 for that single board, a calculation the Board Foot Calculator handles automatically once you enter dimensions and price per board foot.

• Board feet measure volume, not length. A board foot accounts for thickness and width in addition to length, so two boards of equal length can have very different board foot totals.
• Nominal vs. actual dimensions matter. A "2x4" is nominally 2 inches by 4 inches but its actual dressed size is smaller, around 1.5 by 3.5 inches, which affects the true board foot count if precision matters.
• Board feet are additive across an order. When buying multiple boards of different sizes for a project, their board foot totals can be summed to get an overall lumber volume and cost estimate.
• Bulk materials use different volume units. For concrete, gravel, or soil, contractors typically use the Cubic Yard instead of board feet, since those materials are not measured as individual dimensional pieces.
• Price per board foot varies widely by species. Softwood framing lumber costs far less per board foot than hardwoods like oak or walnut, so always confirm the price basis before comparing quotes.