Here's the breakdown:

* Board foot: A unit of measurement for lumber, equal to a piece of wood 1 foot long, 1 foot wide, and 1 inch thick.

* Cubic foot: A unit of volume equal to a cube with sides of 1 foot each.

Since a board foot is 1 inch thick (1/12 of a foot), you need 12 board feet to make up the full 1 foot thickness of a cubic foot.