Rentable Square Footage equals the usable square footage plus the tenant’s pro rata share of the building common areas, such as lobbies, public corridors and restrooms.
As an example calculation, if a tenant’s useable square footage is 10,000 square feet which accounts for 7% of all useable square footage in a building. If the building has 15,000 of common areas, then the tenant’s rentable area is 11,050 square feet (10,000 useable square feet plus 7% of the 15,000 square foot common area). Multi-tenant buildings with common areas such as office buildings and retail centers may charge base rent on rentable square footage and/or collect CAM reimbursements based on rentable square footage since the tenant benefits from the use of the common areas which also incur expenses.