I’m no ultra minimalist but my Stratos 34 litre backpack works like a magic while I travel the world. All my toiletries are Lush solids so packs to a small space (probably even smaller than most men have it). All excess baggage is just putting a strain on the journey and anything more than mid-30 litres would not allow me to see the world as I best could. Then again, I don’t carry a laptop or too many clothes and my fujix100 is smaller than a dslr. This just as a comment to those who wonder whether a 30 something backpack is enough. It surely is!