BRENT C
Assuming I did it right, tape measurer shows the lay-flat dimensions as 20" x 27". It's a cylinder with a base of diameter of 30" and height of 27". Height measured from seam to strap where buckles are, and diameter measured seam-to-seam. Don't gauge volume off of this because you lose capacity when the strap is folded down and the buckles are connected (also, bottom seam looks slightly smaller than diameter of open sack - see pictures of items). Max volume (pi x radius squared x height) = 19,085 cubic inches, but adjust that down as noted. I bought this as a dry bag for the inside of my pack. I'll be using my eVent compression sack instead - this is a good dry bag but it's not flexible enough and I think I can get around it with the event and a pack cover.