Rentable Square Footage (RSF)
The total area a tenant pays rent on, including their usable space plus a proportional share of common areas.
Definition
Rentable square footage is the measurement used to calculate rent in commercial leases. It includes the tenant's usable space plus their pro-rata share of common areas such as lobbies, corridors, restrooms, and mechanical rooms. RSF is calculated by multiplying usable square footage by the building's load factor. In small bay industrial properties, RSF and USF are often identical or nearly so because units typically have direct exterior access and self-contained facilities. Understanding RSF is essential for comparing lease rates across properties—a $12/SF rate on a building with a 1.20 load factor is more expensive than $13/SF on a building with a 1.05 load factor.
Formula
RSF = Usable Square Feet × Load FactorExample
Two buildings advertise similar rates. Building A: $12/RSF with 1.18 load factor. Building B: $13/RSF with 1.05 load factor. For 2,000 USF, Building A costs $28,320/year (2,360 RSF × $12). Building B costs $27,300/year (2,100 RSF × $13). The higher quoted rate is actually cheaper.