If I've packed in I use my Nomad and a #11 pocket, so i'm guessing 2700 cubic inches. That carries everything pretty well. If it's a day hunt kind of thing, then most of my packs are 2800 to 3000 ci. If I was hard pressed, I could get by with 1000 ci. For my back, I like to have a waist belt even on the little packs. I'm pretty fond of the Kifaru Zippy (even though it doesn't have a belt), and tailgunner. I've used Kelty Redwing, REI, no name brands and they all got the job done. Some wore out faster than others though.