8x9 This storage unit is approximately half of the size of an average bedroom. It will hold a couch, chair, chest of drawers, boxes and small items or 85 medium boxes.
10x10 This storage unit is approximately the size of an average bedroom. It will hold about 2 to 3 rooms of furniture or approximately 200 medium boxes or what you would fit in a 15 ft. moving van.
10x20 This storage unit is approximately the size of a one car garage. It will hold about 4 to 5 rooms of furniture or about 400 medium sized boxes or what you would fit in a 24 ft. moving van.
14x20 This storage unit is approximately the size of an over sized garage. It will hold furnishings for a 3 – 4 bedroom house (including appliances), or approximately 500 medium sized boxes or what you would fit into a moving van larger than 24 ft.
10x30 This storage unit is approximately the size of a large over sized garage. It will hold furnishings for a 3 – 4 bedroom house (including appliances), or approximately 600 medium sized boxes or what you would fit into a moving van larger than 26 ft
All of these are just estimates provided to help you get an idea of the size of the units. You may get more or less in them depending on your ability to pack well and the sizes/shapes of your stored items.