Storage space from the size of a small closet to a walk-in closet
If you can see your items fitting in to the size of a standard or walk-in closet, then a 5x5 or 5x10 small storage unit (about 25 or 50 square feet) is the space you're looking for.

Personal Storage Use
Small storage units range in sizes all the way up to a space about the size of a walk-in closet. You'll be able to fit a room of furniture and some boxes, or a 1-bedroom apartment in a small storage unit. you can comfortably store your boxes, chairs, bookcases, and small household furniture.

Business Storage Use
Small storage units can accommodate your business files and records and hold anywhere from 30 to 130 boxes. Small storage units are suitable to store chairs, file cabinets, boxes and small office furniture. Sizes range from 5x5 to 5x15.

Storage space from the size of an average bedroom to a small garage.
If you can see your items fitting in to the size of an average bedroom when everything is packed and stacked up, then a Medium 10x10 storage unit (about 100 square feet) is in the range of what you're looking for.

Personal Storage Use
Medium storage units range in size from a small bedroom-sized unit up to a unit that is approximately the size of a small garage. These units can store everything from a small 1 bedroom apartment to a 2 bedroom home. You can store chairs, sofas, desks, a mattress and frame, and boxes in this space.

Business Storage Use
Medium storage units can hold anywhere from 100 to 290 boxes, You can store desks, cabinets, computers, printers, copiers and other medium-sized office equipment in this space.