Self Storage Unit Sizes Explained: Which Size Do You Need?

By KO Storage Content Team

In This Post

How storage unit sizes are measured
What fits in a 5x5, 5x10, 10x10, and 10x20
Larger sizes and vehicle parking units
How to choose the right size without guessing

The hardest part of renting a storage unit is not finding one. It is figuring out which size to rent so you are not paying for space you do not need, or cramming everything into a unit that is too small.

Storage unit sizes follow a simple width-by-depth naming system. A 10x10 is 10 feet wide and 10 feet deep, with a standard 8-foot ceiling. Here is what each size can actually hold.

How Storage Units Are Measured

Unit sizes are listed as width x depth in feet. A 5x5 gives you 25 square feet of floor space. A 10x20 gives you 200. Most units have 8-foot ceilings, so vertical stacking adds meaningful capacity beyond the floor footprint.

When comparing sizes, keep in mind that the usable space is a bit less than the raw square footage once you account for moving room. If you are on the fence between two sizes, it is almost always worth going one size up. The cost difference between adjacent sizes is usually small. The cost of a unit that is too small is a second trip, a second rental, and the time involved.

5x5: The Small Unit

Think of a large walk-in closet. A 5x5 is 25 square feet and works well for smaller, defined storage needs.

Fits well:

Boxes of off-season clothing or seasonal items
Small appliances and kitchen extras
Holiday decor and garden tools
Business records, files, and office supplies
A bicycle, set of golf clubs, or similar sporting gear

Best for: students storing between semesters, homeowners decluttering one room, or businesses archiving documents they rarely need to access.

5x10: The Starter Unit

The 5x10 is roughly the size of a small bedroom or a large walk-in closet. The extra five feet makes a significant difference in what you can fit.

Fits well:

A full mattress and box spring plus several boxes
A couch or loveseat and a coffee table
Most of the contents of a studio apartment if packed efficiently
A motorcycle or small trailer

Best for: someone between apartments, a one-room move, or a homeowner storing the contents of one bedroom during a renovation.

10x10: The Most Popular Size

The 10x10 is the most commonly rented unit size, and for good reason. At 100 square feet, it holds the contents of a one-bedroom apartment with room to move around.

Fits well:

Full bedroom set: bed frame, mattress, dresser, and nightstands
Living room furniture: couch, coffee table, and TV
Kitchen appliances and boxes of household goods
A small business's inventory, equipment, or files

Best for: a one- to two-bedroom move, a household in transition, or a business needing overflow storage. If you are unsure between sizes and your storage needs fall somewhere in the middle range, the 10x10 is the safer starting point.

10x20: The Large Unit

The 10x20 is the size you need when you are storing the full contents of a house. At 200 square feet, it is roughly equivalent to a one-car garage.

Fits well:

Furniture from a two- to three-bedroom home, including multiple bedroom sets
Full living room and dining room sets
Large appliances: washer, dryer, refrigerator
Boxes, totes, and everything else from a full household

Best for: a family home in transition, a cross-country relocation, a full estate clearance, or a business storing large equipment and significant inventory.

Larger Sizes and Vehicle Parking

KO Storage facilities offer unit sizes up to 10x30 at select locations, as well as outdoor and covered parking spaces for vehicles, RVs, trailers, and boats. Parking spaces vary by facility and can accommodate vehicles from compact cars to larger motorhomes, depending on the location.

If you need vehicle storage, confirm the specific size and access type available at the location you are considering before reserving. Covered parking is available at select facilities and offers UV and weather protection for longer storage periods.

Choosing the Right Size

Start with your largest item. If it fits in a 5x10, that is your minimum. Then estimate your remaining items in terms of standard moving boxes (a 10x10 comfortably holds 20 to 30 medium boxes plus furniture).

When in doubt, go one size up. The difference in monthly cost is usually worth the additional space and the flexibility it gives you to pack without precision. KO Storage's size guide walks through each unit size with visual comparisons, which can help you make a confident choice before you arrive.

Ready To Reserve?

Ready to rent? KO Storage has locations across the U.S. with flexible unit sizes and month-to-month leasing. Find a KO Storage facility near you and reserve online with no credit card required.