CRE glossary
Usable area / usable square feet (USF)
Usable area (or usable square feet, USF) is the actual floor area inside the demising walls of a commercial space, the area tenants can use for desks, offices, conference rooms, and operations. USF excludes shared corridors, restrooms, building lobbies, and mechanical rooms. USF + pro-rata share of common areas = rentable square feet (RSF).
USF is the truth measurement of how much space the tenant gets to use. Rent is quoted on RSF (which includes common areas allocated pro-rata), but space planning and headcount calculations are done on USF. A 12,000 RSF suite with a 16% load factor is 10,344 USF, that's the actual planning area.
Modern tenant-rep brokers tour buildings on USF, not RSF. Two buildings quoting the same $/RSF rent with different load factors give different USF outcomes, and the USF is what determines whether the space actually fits the tenant's headcount. A 22% load factor building wastes 22% of every rent dollar on common area.
BOMA (Building Owners and Managers Association) defines USF measurement standards. Reputable buildings get measured every 5–10 years; older or undermanaged buildings can have legacy errors that overstate USF (and thus understate the load factor), verify by checking the BOMA report before LOI.
Example
- Suite 1800 RSF
- 12,150 SF
- Suite 1800 USF
- 10,420 SF
- Load factor
- 16.6%
- Rent at $58/SF on RSF
- $58 × 12,150 = $704,700/yr
- Effective rent on USF
- $67.63/USF
Broker perspective
Always compare buildings on $/USF, not $/RSF. The cheapest $/RSF is rarely the cheapest $/USF. The conversation becomes 'which building gives you the most usable space per dollar' instead of 'which has the lowest headline rate', and you'll pick a different winner half the time.
Frequently asked
People also ask
Do I pay rent on USF or RSF?
RSF. Always. The load factor is built in.
Why does USF matter if I pay on RSF?
Because USF is what you can actually use. Headcount, layout, operations all depend on USF, but rent is on RSF.
Can I negotiate USF?
No, it's a building-level measurement. But you can negotiate rent down if the load factor is high.
How is USF measured?
BOMA standards. Inside the demising walls, excluding common areas. Reputable buildings remeasure every 5–10 years.
Related terms
Rentable vs usable square feet (RSF / USF)
USF is the floor area you can actually use; RSF adds your share of common areas. The ratio between them is the load factor.
Load factor
The percentage of common-area square feet allocated to the tenant on top of usable space, typically 12–18% in Class A office.
Base rent
The headline rent before pass-through expenses, usually quoted in $/SF/year and the starting point for every comp.
Demising wall
The wall separating one tenant's premises from another tenant's or from common areas, defines the leased space boundary.
See usable area / usable square feet (usf) extracted from a real lease.
Drop a 60-page lease, get a 38-field abstract in 90 seconds, every value cited back to the source page.