How Do You Figure Board Feet?

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Much of the wood you buy in home improvement stores is softwood and sold as dimensional lumber, but suppliers sell hardwood by the board foot. Board foot is a measure of volume; each board foot is equal to 1/12 of a cubic foot. Figure board feet using a tape measure and calculator. Measurements used in calculating board feet are for the rough-cut lumber dimension and not the actual finished lumber size.

  1. Measure the thickness of the board

    Measure the thickness of the board using quarters of an inch. The thickness of boards over 1 inch is expressed as an improper fraction, so a 1 1/2-inch stock is 6/4 lumber.

  2. Measure the length and width of each board

    Use the tape measure to determine the width of the board in inches. Measure the length using either feet or inches.

  3. Calculate the volume in board feet

    Use the formula to find volume of board feet: (length x width x thickness)/144. If you measured the length in feet, divide the product by 12.

  4. Calculate the cost of the lumber

    Multiply board feet by the stated price to determine the cost. Because of the expense of hardwoods, small differences in rounding cause a significant difference in the actual cost of the board.