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.
- 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.
- 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.
- 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.
- 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.