Woodworking, Hardwood
Buying hardwood is done by the “board foot”. One board foot is a 12” x 12” x 1” volume of rough cut lumber.
Rough cut planks are dimensioned in “quarters” (of an inch). So 4/4 lumber (four quarters) is rough cut 1” thick.
So a 9 foot plank of 8/4 maple, 4” wide, is 6 board feet. (9 * 4/12 * 2)