Convert from board foot to cord [firewood]

Unit Definition (board foot)
The board foot is a unit of volume used for measuring lumber. One board foot is the volume of a one-foot length of a "standard board" twelve inches wide by one inch thick. Thus a board foot equals 144 cubic inches, or 1/12 of a cubic foot, or approximately 2.360 liters. If lumber is stacked neatly, we can compute the number of board feet from the dimensions of the stack, no matter how wide or thick the boards are. For example, a stack of two-by-fours 4 ft high, 4 ft wide, and 8 ft long contains 4 x 4 x 8 = 128 cubic feet, equivalent to 128 x 12 = 1536 board feet. The symbol fbm is an abbreviation for "foot, board measure."

Unit Definition (cord [firewood])
The cord [firewood] is a traditional unit of volume used to measure stacked firewood. Like most traditional units of trade, the cord has varied somewhat according to local custom. In the United States, the cord is defined legally as the volume of a stack of firewood 4 feet wide, 8 feet long, and 4 feet high. (In Maryland, the law specifies that the wood be stacked "tight enough that a chipmunk cannot run through it." Presumably it is up to the buyer to provide the chipmunk.) One cord is a volume of 128 cubic feet, about 3.6246 cubic meters, or 3.6246 steres. The name apparently comes from an old method of measuring a stack of firewood using a cord or string.