I don't know. Can't you at least figure that out? I mean the bags of medium you're buying are labeled with the amount of soil they contain, no? I've given you all of the mathematical calculations you'll need regardless of how the company that makes your preferred soil state the volume.
I've got no clue what size or types of bags or bails the soil you're going to use will hold. My medium comes in 60lb, 3.8 cu/ft bails. Take that into consideration if you're going to be carrying those around.