It's 3.8cf when it's uncompressed, I THINK. I use the the plain peat by the same co, 3.8 cf bag and it really expands when uncompressed.would i use 1 bale 3.8 cf or 2 bales of pro mix to subcools ss recipe? is a bale still 3.8 cf when its uncompressed, i've never opened one up. thanks