What size storage unit do you need? Check-out our storage unit size guide series to find the right size for your storage needs. A 10x10 self storage unit can hold the content of a two bedroom apartment. It is about the space of a large family room, or two extra bedrooms. Leave a comment below and we can help find the right unit size for you! How to choose the best unit size: 1. Make a list of all the items that will go into storage 2. Measure the length, width, and height of larger items. 3. Use