BOMA Standards Explained: Usable (USF) vs. Rentable Square Feet (RSF)

When negotiating a commercial office, retail, or industrial lease, one of the most critical terms on the lease agreement is Rentable Square Footage (RSF) vs. Usable Square Footage (USF).

A business tenant leasing a "5,000 RSF office" may be surprised to measure their private suite and find only 4,200 square feet of actual desk space. Understanding BOMA Measurement Standards protects commercial tenants from overpaying for shared space.

What is BOMA Standard?

The Building Owners and Managers Association (BOMA) International publishes standardized measurement methods (such as BOMA Z65.1 for Office Buildings). BOMA standards dictate how landlords, architects, and brokers measure commercial buildings to establish fair lease allocations.

Usable (USF) vs. Rentable (RSF) Defined

• Usable Square Footage (USF): The physical area within the suite boundaries that your business occupies exclusively. It includes carpet space, private offices, internal conference rooms, and private restrooms.
• Rentable Square Footage (RSF): The total area for which you pay rent. It equals your USF plus your pro-rata share of the building's shared common areas (main entrance lobby, public restrooms, mechanical rooms, elevator banks).

Rentable Sq Ft (RSF) = Usable Sq Ft (USF) × (1 + Load Factor)

The Load Factor (Loss Factor / Core Factor)

The Load Factor represents the ratio of common area added to each tenant's usable area:

Load Factor = (Total Building Common Area ÷ Total Building Usable Area)

Typical load factors by property type:

• Suburban Office Park: 12% to 18%
• High-Rise Downtown Office: 15% to 22%
• Retail Strip Center: 0% to 5% (direct street access)
• Industrial Warehouse: 3% to 8%

Rentable vs. Usable Cost Comparison Table

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