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Usable vs Rentable Area Calculator
Landlords quote in rentable SF — the billable number. Tenants occupy usable SF — the actual inside-the-demise area. This calculator divides RSF by load factor to get USF and shows effective rent per USF, the only fair way to compare competing office spaces.
Usable SF
13,043
Common area SF
1,957
Common area share of RSF
13.04%
Effective rent / USF / year
$40.25
Annual rent on RSF
$525,000
How the math works
Quick RSF-to-USF conversion: divide by load factor. A 15,000 RSF lease at 1.15 load = 13,043 USF. Tenant pays rent on 15,000 but only 13,043 is actually inside their demise — everything else is common area.
Always compare buildings on effective $/USF, not headline $/RSF. Class A vs Class B differences often disappear once you normalize for load factor.
How to Use
- Enter quoted rentable SF.
- Enter the building's load factor.
- Enter rent per rentable SF per year.
- Read usable SF, common area SF, and effective rent per USF.
Frequently Asked Questions
Why do landlords quote RSF?
Rentable SF includes a share of common areas that tenants benefit from — lobbies, restrooms, corridors. The load factor monetizes those benefits. But for comparison purposes, USF is always the better apples-to-apples number.
How to benchmark load?
Class A high-rise: 1.10-1.18. Class B: 1.12-1.20. Garden office: 1.05-1.10 (single-tenant or full-floor dominant). Anything over 1.20 is aggressive and should be negotiated down or offset with rent concession.
USF vs net usable area?
Usable SF = space the tenant controls including interior walls. Net usable area = USF minus interior walls/columns. Architects use NUA for layout planning; leases use USF.
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