Measure the length from top to bottom, width across and thickness of the board using a measuring tape. Convert all measurements to inches.
Multiply the length, width and depth. For a board that is 72 inches long, 8 inches wide and 2 inches deep, the result is 1,152.
When using inches in the calculation, divide by 144, according to The Hardwood Store of North Carolina. In the example, 1,152 divided by 144 results in 8 board feet.