Useable Square Feet
Useable square footage is the actual space you occupy from wall to wall. Usable square footage does not include common areas of a building such as lobbies, restrooms, shared breakrooms, stairwells, storage rooms, and shared hallways.

Rentable Square Feet
Rentable square footage is your usable square footage PLUS a portion of the building’s shared space. Shared space can be anything that is outside of your occupied space and is of benefit to you (lobbies, restrooms, breakrooms, hallways, etc). As a tenant in a commercial space, you pay for a portion of the shared space and thus your monthly rent is always calculated on RSF.

The rentable square footage is generally 10% - 20% higher than useable square footage. When evaluating commercial real estate space options, you’ll want to be aware of this difference so you know exactly what you’re getting and what you’re paying for.

Lastly, it’s important to be aware and understand the difference of useable square footage and rentable square footage when comparing the costs per square foot of available commercial office space. Not all commercial property owners specify which square footage definition they are advertising.