no one knows, its better that way the maximum amount that it could possibily be would be 128 cu/ft.  it is a volume measurement.  to prevent the wood from going bad it needs to be stacked so that a mouse can move freely through the wood pile.  to insure that the wood is stacked properly i use a three minute test mouse.  if he can get throught the wood pile in three minutes, it is stacked properly. 

the mouse works cheap i give him/her goldfish treats as payment.