A 5x10 storage unit would be good to store medium boxes, mattresses, chairs, and sports equipment. If you are storing moving boxes, you can expect to fit up to 20 boxes of varying sizes in this unit.

A 10x10 unit is a good size for the stuff found in two bedrooms, an entire family room or a modest one or two-bedroom apartment. A few large appliances and pieces of large furniture can easily be stored in a 10x10 storage unit as well as mattress sets, desks, couches, dining room sets and multiple boxes.

A 10x15 in size can easily accommodate bigger items, such as couches, tables, beds, dressers, and even pianos. With so much space, you'll have no trouble storing lamps, desks, and TVs, along with kitchen appliances like microwaves and refrigerators.

A 10x20 storage unit is great for storing contents of a multi-bedroom home, about up to five rooms of space. Larger items like living room furniture, patio furniture, full-sized appliances and more fit inside these units. 10x20 storage units also work well for storing large quantities of boxes or outdoor equipment.
10x20 units are also recommended if you are looking to store a vehicle!

The 10x24 unit is ideal for keeping all the items of a four or five-bedroom home. It can fit bedroom furniture from multiple rooms, living room furniture including a four to six-person dining room set, plus a washer and dryer, a refrigerator, clothing, shoes, household items, patio furniture and sports equipment.

Common items you can store in a 10x40 unit are large household appliances like refrigerators, living room furniture sets, four or five bedroom sets, a four to six person dining room set, large-screen TVs, patio furniture, office furniture, and garage extras.

This unit has 3 doors that access one large unit.
A 15x15 in size can easily accommodate items such as couches, tables, beds, dressers, etc.
With an extra 5 feet of space compared to a 10x15 you'll have no trouble storing items from a household.