Visualising a cubic foot, which is what you asked. Imagine a 12 foot long board which is 12 inches wide and 1 inch thick, if you were to cut it into 12 and stack them up that would be a cubic foot. Ian
As said earlier wastage factors are probably the biggest issue to consider. This will depend on a number of factors including
Species type. Is the sap wood includes and is it usable Some species such as yew contain lots of defects which you may be able to include or otherwise
2 square edge boards often cost a bit more but you will get a bigger yield than from waney edge boards
Your cutting list and board dimensions. If you need board say 4 inches wide X 48 inches long and you can only but 7 foot boards 7 inches wide you are going to have a lot of wastage (but good to use for other projects etc) conversely 9 foot boards 9 inches wide and and you will get 4 pieces out of a board with minimal overage.