Storage units are a good way for you to keep belongings you want but don't have space to keep at home. The units come in various sizes, so you should have no problem finding the one that is the right size for you. The problem is trying to figure out what size unit you need. The units are sized by square feet; for example, a unit may be 8 feet by 10 feet, giving you a unit of 80 sq feet, but that doesn't necessarily tell you how much stuff you can fit in the unit or how big the unit really is.