I would not put so much reliance on the hip belt taking the weight of your backpack or on buying a larger backpack than you actually need...I'm 6 foot 1 inch tall which means my M.H. Scrambler RT35 is several inches shorter than my torso length and this means the hip belt does not actually reach down to my hips...It is really there to just to hold it securely to my back, so the pack doesn't wobble around as I walk...If it does that you are not just wasting energy but it can chaff your shoulders and/or your back leaving you feeling uncomfortable. My RT35 is big enough for all my kit, and even at a weight of just over 10kg it is extremely comfortable to hike with...even when I am only wearing a thin, ultralight, Polyester walking T-Shirt. I use the latter because it's much lighter than a Cotton T-shirt, quickly wicks away any sweat, and because it's also quick drying. By the way, I always use the chest strap, both to hold the shoulder straps in the most comfortable position, but to also take some of the weight off my shoulders and distribute some of it across my chest, so use every strap provided and adjust them properly. I found that when I adjusted the shoulder straps for maximum length, because of my tall torso length, the backpack was wobbling around a lot as I walked, which was very uncomfortable, even for a few hundred yards...Instead, I pulled the top adjuster straps tight to shorten the shoulder straps to their minimum length and the pack stopped wobbling altogether and it sort of became part of my body, rather than something foreign hanging off it, if that makes sense...So proper adjustment is far more important than the size of the pack.