A storage bag includes first and second sidewalls that are directly connected without a pleat between the sidewalls at a bottom of the bag. The bag includes a plurality of shift regions at bottom portions of the sidewalls. The bag can be moved about the shift regions such that the bag is shiftable between a flat configuration with the first and second sidewalls positioned adjacent to each other and a stand-up configuration with the first and second sidewalls separated from each other. In the stand-up configuration, the bag is shifted about the shift regions such that a substantially flat base is formed for the bag.