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Units of Measureaka: BFaka: bd ftaka: FBM (feet board measure)

Board Foot

In Plain English

A unit for measuring lumber volume equal to a 1-foot square piece of wood that is 1 inch thick.

Definition

A board foot is a unit of measure for lumber equal to the volume of a piece of wood one foot long, one foot wide, and one inch thick—equivalent to 144 cubic inches. Lumber is priced and sold by the board foot, and estimators use board feet to quantify and price rough lumber for framing, formwork, and millwork. To calculate board feet: (thickness in inches × width in inches × length in feet) ÷ 12.

Why It Matters in Bidding

Lumber is bought and sold by the board foot, so estimators must convert framing, formwork, and millwork takeoffs into board feet to price material accurately and compare supplier quotes on equal footing. Small conversion errors multiply across thousands of pieces, swinging a wood-framed bid by thousands of dollars and eroding margin if waste factors are misjudged.

Example

Pricing a deck and pergola, the estimator tallies the framing lumber at 2,400 board feet, adds a 10 percent waste factor, and multiplies by the supplier's per-board-foot rate to land the rough-lumber line item.

Related Terms

Linear FootSquare FootUnit Price

Frequently Asked Questions

Multiply nominal thickness in inches by width in inches by length in feet, then divide by 12. Tally each lumber size separately, sum the totals, and add a waste factor for cutting and damage. Estimators then multiply the net board-foot quantity by the supplier's unit price to build the material line item.
Board feet normalize different dimensions into a single volume unit, letting buyers compare prices across thicknesses and widths consistently. A piece-based quote would hide how much actual wood you're buying. Pricing by volume also lets suppliers reflect grade and species value uniformly, helping estimators evaluate competing bids on a true cost-per-volume basis.
Board-foot calculations conventionally use nominal dimensions, such as a 2x4 counted as two by four inches, even though the dressed lumber is smaller. Suppliers price on this nominal basis, so estimators should match the convention to avoid underbuying. Confirm with the supplier when in doubt, since rough versus surfaced material can affect the count.

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