Well let's see what would bump up the cost...  More materials.  This is actually minor cost on low end garments, more on things like leather jackets. More labor.  Hems are longer and they can produce fewer garments an hour. More shipping.  Since most items are shipped via cargo ships, this probably is only 10 cents more for the ocean, but can drastically more to ship to the final customer if ordered online. More space taken in warehouses. Fat's returning more items cause nothing fits them.  The only reason more garments aren't priced for every size is cause there is a cost associated with pricing every item at stores.     The scary thought behind my thought of line is of course that eventually those plus-sizes will become normal and cheap like other sizes, and smaller sizes in turn would have to pay extra.  This is likely to happen.  It will be normal, but it won't be cheap.  They'll drag all the prices up as (1-5) don't go away even if it's normal.