5x12 storage units are perfect for both residential and commercial self-storage needs, such as using storage while moving to a new home, decluttering an office space, storing college dorm room items, and more. At Extra Space Storage, these storage units are similar in size to a walk-in closet. 5x12 units can typically hold the contents of a small bedroom or dorm room, such as a dresser, TV, queen-size mattress set, and several boxes.