Commercial Real Estate Made Simple
Rentable vs. Usable Square Footage in Commercial Real Estate
A practical guide to usable square footage, rentable square footage, load factors, common areas, and why two commercial spaces with the same quoted size may provide very different amounts of working space.
What Is the Difference Between Rentable and Usable Square Footage?
In commercial real estate, the square footage shown in a listing or lease proposal may not be the exact amount of space located inside a tenant’s suite. Two measurements are especially important: usable square footage (USF) and rentable square footage (RSF).
Usable square footage generally describes the area a tenant can use exclusively inside its premises. Rentable square footage generally includes that usable area plus an allocated share of certain building common areas, depending on the property, measurement method, and lease.
What Is Usable Square Footage?
Usable square footage generally refers to the space located within the boundaries of the tenant’s premises that the tenant can use for its own operation. In an office, that may include private offices, workstations, conference rooms, reception, internal circulation, storage, break areas, and other space located inside the suite.
The exact measurement can depend on the building type and the measurement standard being used, so tenants should confirm how the stated usable area was calculated.
What Is Rentable Square Footage?
Rentable square footage is commonly the square-footage figure used to calculate rent in multi-tenant commercial buildings. It generally starts with usable square footage and adds an allocated share of certain common areas used by tenants throughout the building.
Depending on the property and measurement method, common areas may include portions of:
- Building lobbies
- Shared corridors and hallways
- Shared restrooms
- Elevator lobbies
- Stairwells
- Other shared building-service or circulation areas
Why Can Two 5,000-Square-Foot Spaces Feel Very Different?
A 5,000-RSF suite in one building may provide more usable interior area than a 5,000-RSF suite in another building. The difference can come from the building’s common-area allocation, floor configuration, core layout, measurement method, and how efficiently the suite itself is laid out.
That is why businesses comparing office space in Michigan should look beyond the headline square footage and evaluate how much space is actually available for employees, meetings, storage, reception, circulation, and other day-to-day needs.
What Is a Load Factor?
The term load factor is commonly used to describe the relationship between a tenant’s usable area and its rentable area after common space is allocated. Terminology and formulas can vary by lease and measurement convention, so the lease documents and measurement method should control.
For the simplified examples in this guide, a 20% add-on/load factor means the usable area is multiplied by 1.20 to estimate the rentable area.
Simple Rentable Square Footage Example
Assume an office suite contains 4,000 usable square feet and the simplified add-on/load factor is 20%.
In this simplified example, 4,000 usable SF × 1.20 = 4,800 rentable SF. The additional 800 square feet represents the allocated building-common-area component used in this example.
How Does Rentable Square Footage Affect Rent?
In many office leases, the quoted rental rate is applied to rentable square footage rather than usable square footage. That can materially affect the annual and monthly rent a business pays.
For example, if a suite has 4,000 usable square feet but 4,800 rentable square feet, a quoted rental rate may be applied to the 4,800-RSF figure. The lease should clearly identify the measurement used to calculate rent.
Why Occupancy Efficiency Matters
When two properties have similar asking rates and similar rentable square footage, the more efficient layout may provide more productive space for the same quoted size. That can affect how many employees, offices, meeting rooms, workstations, and support areas the business can actually accommodate.
Businesses should compare the usable area, rentable area, layout, common-area allocation, buildout requirements, and total occupancy cost rather than choosing a property based on one number alone.
How Does This Connect to CAM, NNN, and Total Occupancy Cost?
Square-footage measurement is only one part of lease economics. Tenants should also understand whether operating expenses, taxes, insurance, or other pass-through costs are charged in addition to base rent.
Our guides to NNN leases and CAM charges explain two common cost concepts that can affect total occupancy expense. If a space requires construction, our guide to tenant improvement allowances explains another important part of the lease.
What Should a Tenant Ask Before Signing a Lease?
- What is the usable square footage? Confirm the area your business will occupy exclusively.
- What is the rentable square footage? Confirm the square footage used to calculate rent.
- What load or add-on factor is being used? Understand how the rentable number relates to the usable area.
- How was the space measured? Ask what measurement standard or method was used.
- What common areas are included? Understand which shared spaces contribute to the rentable calculation.
- Are other charges also based on rentable square footage? Confirm how operating expenses and other charges are calculated.
- Has the space been independently verified? If square footage is critical to the transaction, consider appropriate professional verification.
How This Fits Into an Office-Space Search
Rentable and usable square footage should be evaluated together with location, parking, layout, technology, HVAC, building condition, lease structure, and future growth. Our office-space evaluation guide walks through those broader considerations before a business commits to a lease.
Businesses still deciding whether leasing is the right long-term strategy can also review our lease vs. buy commercial property in Michigan guide.
How a Commercial Real Estate Broker Can Help
A commercial real estate broker can help a business compare available spaces based on more than advertised square footage. That can include reviewing usable and rentable area, asking rates, operating expenses, layout efficiency, buildout, location, parking, and other factors that affect the overall value of a property.
Crabill & Company provides commercial real estate brokerage services for businesses, property owners, investors, and developers throughout Michigan.
Rentable vs. Usable Square Footage FAQs
What is usable square footage?
Usable square footage generally refers to the space within a tenant’s premises that the tenant can use exclusively for its operation.
What is rentable square footage?
Rentable square footage generally includes the tenant’s usable area plus an allocated share of certain building common areas, depending on the measurement method and lease.
Is rent usually based on usable or rentable square footage?
In many multi-tenant office leases, rent is calculated using rentable square footage. The lease should clearly identify the square-footage figure used for rent and other charges.
What is a load factor in commercial real estate?
Load factor is a term commonly used to describe the relationship between usable area and rentable area after shared building space is allocated. Definitions and formulas can vary, so the lease and measurement method should be reviewed.
Can two spaces with the same rentable square footage have different usable square footage?
Yes. Differences in building common areas, floor configuration, measurement method, and layout efficiency can result in different amounts of usable tenant space.
How should I compare two office spaces with different load factors?
Compare the usable area, rentable area, rental rate, layout efficiency, operating expenses, buildout requirements, and total occupancy cost rather than relying on rentable square footage alone.
Comparing Commercial Space in Michigan?
Explore current Crabill & Company listings or contact our team to discuss your location, square footage, layout, parking, buildout, and lease requirements.