Phones have a bigger footprint but a 10k or 12k battery back is MUCH thicker and MUCH heavier. Take it from someone with a big phone AND a 12k battery pack; only one of those happily lives in my pocket all day. Maybe on something with cargo pockets you could stick the battery in a pocket but it wouldn't be comfortable to sit on it.People stuff 6" 'phones' in their pockets. I've seen 10Ah power banks smaller than those but haven't tested one yet to see if they can actually deliver. I do plan to address that later this year.