I agree with Dan_Mcl; make sure the the bag fits you. Any bag can hold stuff, you need to hold the bag. If it fits poorly you are in for a world of hurt. If you don't already have your BOB items separated ou,t then I would suggest that you take a medium-sized suitcase and start chucking your stuff in there. This gives you an idea of volume. Leave a little room for seasonal variations. This will let you see what size bag you are in search of. No need to buy a military duffel bag with straps 'cuz it holds gobs'o'stuff.