Gross Leasable Area (GLA): Definition and CAM Impact
Gross Leasable Area (GLA) is the total floor area of a property available for tenant lease and use, measured from the outside face of exterior walls (or from the center line of shared walls). It is the denominator in the pro-rata CAM share calculation for most retail shopping centers: your CAM obligation equals your leased square footage divided by the GLA, multiplied by the total CAM cost pool.
Because GLA sits in the denominator, any change to the reported GLA directly changes every tenant's CAM obligation. A smaller GLA denominator means each tenant pays a larger share of the same cost pool. Landlords control the GLA figure reported in reconciliations, and the lease's definition of GLA determines whether anchor exclusions, vacant space, and certain non-retail areas factor into the denominator.
Understanding what GLA is, how it is measured, and how it can be modified through lease definitions is essential for any tenant who wants to verify their CAM charges independently.
The BOMA Standard for GLA Measurement
The Building Owners and Managers Association (BOMA) publishes measurement standards that govern how commercial space is calculated. For retail properties, BOMA's "Standard Methods of Measurement: Retail Buildings" (BOMA 2010 Retail and its revisions) defines how GLA is measured and what areas are included or excluded.
Under BOMA retail standards, GLA includes:
- All areas designed for tenant occupancy and exclusive use
- Areas measured from the inside face of exterior building walls to the center line of interior demising walls
BOMA retail measurement differs from office measurement standards (BOMA 2017 Office) in how common areas are treated. In retail, most common areas (mall corridors, food courts, common restrooms) are excluded from GLA entirely because they are not individually leased. Each tenant's leasable area is measured only to the boundary of their demised space.
What this means for CAM calculations: The GLA denominator in a retail lease is typically the aggregate of all tenant spaces, not the entire building footprint. When anchor spaces, storage areas, kiosks, or management offices are excluded from the GLA definition in your lease, the denominator shrinks accordingly.
Most lease definitions of GLA reference BOMA standards for measurement methodology while adding property-specific modifications, anchor exclusions, cap limitations, and occupied-only definitions, on top of the standard. The BOMA measurement governs the size of each individual space. The lease definition governs which spaces are counted in the denominator.
GLA vs. GLOA: The Occupied-Only Distinction
Gross Leasable Occupied Area (GLOA) is GLA limited to only the spaces actually leased and occupied by tenants. Vacant space is excluded from the GLOA denominator.
This distinction matters enormously for CAM allocation.
GLA denominator: Total leasable space regardless of vacancy. If 20,000 SF is vacant in a 200,000 SF center, each tenant's share is calculated against the full 200,000 SF denominator. A tenant with 6,000 SF has a 3% share.
GLOA denominator: Only occupied space. Using the same example, the denominator is 180,000 SF and the same 6,000 SF tenant has a 3.33% share. If the CAM pool is $1,000,000, the difference is $3,000 in annual CAM for that one tenant on that one vacancy scenario.
In centers with significant vacancy, the GLOA denominator shifts the cost of empty space from the landlord to the occupied tenants. This is economically equivalent to the landlord passing through the CAM costs for vacant spaces. The landlord collects no rent or reimbursement from vacant space but uses the GLOA denominator to make the occupied tenants cover the full cost pool.
Which denominator protects tenants? GLA. Using total GLA including vacant space means the landlord absorbs the cost of vacancy rather than passing it through. When negotiating, push for GLA (total leasable area, including vacant space) rather than GLOA. Landlords will often prefer GLOA and may call it "occupied area" or define it without naming the distinction explicitly. Read the denominator definition closely.
Verify your denominator using the pro-rata share calculator before accepting any reconciliation.
How Anchor Exclusions Distort GLA
Anchor tenants, whether they are grocery chains, department stores, or home improvement retailers, frequently negotiate to be excluded from the GLA denominator that applies to other tenants. This is the anchor exclusion, and it is the most significant distortion mechanism in retail CAM math.
A concrete numeric example: Consider a 200,000 SF shopping center with the following structure:
- Anchor tenant A: 50,000 SF (pays fixed CAM, excluded from denominator)
- Anchor tenant B: 30,000 SF (maintains own area, excluded from denominator)
- Inline tenants: 120,000 SF (subject to pro-rata CAM)
Total GLA by measurement: 200,000 SF Denominator as defined in the lease after anchor exclusions: 120,000 SF
A tenant with 6,000 SF:
- Pro-rata share if GLA denominator is 200,000 SF: 3.0%
- Pro-rata share if denominator is 120,000 SF: 5.0%
On a $1,000,000 annual CAM pool, the difference is $20,000 per year. Over a 10-year lease, that is $200,000 in excess CAM attributable entirely to the denominator definition, not to any change in the tenant's space or the total CAM costs.
The scale effect: When anchor spaces represent a large percentage of total GLA, the distortion is proportional. In the example above, anchors hold 80,000 SF out of 200,000 SF, or 40% of total GLA. Excluding them inflates each inline tenant's share by 40% relative to a GLA-based calculation using the full center.
In many power centers and community shopping centers, anchor-occupied or anchor-excluded space represents 40 to 60% of total GLA. Inline tenants in these centers are routinely paying 1.5 to 2.5 times what they would pay if the full GLA were used as the denominator.
How Vacancy Adjustments Interact with GLA
When vacant space is excluded from the denominator, the interaction with anchor exclusions compounds the effect.
Using the same 200,000 SF center:
- Anchor exclusion: 80,000 SF excluded
- Inline vacancy: 15,000 SF excluded (GLOA denominator)
- Effective denominator: 105,000 SF
Your 6,000 SF space:
- Share against full 200,000 SF GLA: 3.0%
- Share against 105,000 SF (anchors + vacancy excluded): 5.71%
CAM on the $1,000,000 pool: $57,100 instead of $30,000. A $27,100 annual difference from denominator mechanics alone.
This compounding effect is why the lease definition of GLA, and specifically whether it uses GLA or GLOA and whether anchor exclusions apply, is one of the highest-value items to negotiate before signing.
Requesting GLA Documentation from the Landlord
Your lease should include an audit rights clause that gives you access to the landlord's CAM records. For GLA-related verification, you need specific documents:
The GLA schedule or exhibit. Many leases attach a GLA exhibit as Exhibit B or Exhibit C listing each tenant space by suite number, square footage, and whether it is included in or excluded from the CAM denominator. Request this exhibit at signing and retain it. If it changes during your lease term, you need to know.
The annual reconciliation's denominator disclosure. The reconciliation statement should state, explicitly, the denominator used to calculate your pro-rata share for the reconciliation year. If it does not, request the supporting worksheet that shows the calculation. You are entitled to this under most audit rights clauses.
The building measurement certificate. For new leases in properties that have been recently measured, a BOMA measurement certificate from a licensed architect or surveyor establishes the authoritative GLA figure. If the landlord's reported GLA differs materially from the BOMA measurement, investigate why.
Comparison year-over-year. Track the reported GLA denominator from each year's reconciliation. If the denominator is declining year over year without new anchor exclusions being added, ask for an explanation. Landlords sometimes reclassify space from the denominator to reduce their own exposure to the CAM pool without communicating the change.
Pro-Rata Share Error: The Most Common CAM Overcharge Pattern
Pro-rata denominator error is one of the most common findings in commercial CAM audits. The error takes several forms:
Incorrect denominator applied. The landlord uses a denominator that differs from the contractual definition. This can result from system defaults, reconciliation template errors, or deliberate application of a GLOA denominator when the lease specifies GLA.
Anchor exclusion applied without contractual basis. The landlord excludes an anchor from the denominator even though the lease does not specifically authorize that exclusion. This requires checking the lease's GLA definition against the denominator used.
Square footage discrepancy. The reported GLA for the denominator differs from the sum of individual tenant spaces disclosed elsewhere in the reconciliation. A landlord who lists 120,000 SF of inline tenant space in Exhibit A but uses a 110,000 SF denominator has a discrepancy that requires explanation.
Mid-year denominator changes. Some landlords change the denominator mid-year when a major tenant vacates or a new anchor opens. If the denominator changes mid-year, the reconciliation should disclose this and the annual CAM calculation should use a weighted average denominator. Applying a year-end denominator to the full year is a common error.
After testing reconciliation samples from published audit cases through CAMAudit, pro-rata denominator errors appear in a significant share of retail CAM reconciliations. The pro-rata share calculator tool can help you run an independent check against the landlord's reported denominator.
Verifying the Number: A Step-by-Step Approach
Pull your lease's GLA definition. Find the definition section that defines "Gross Leasable Area," "Total Leasable Area," or the denominator term used in your pro-rata clause. Note whether it is GLA or GLOA, which tenants are excluded, and whether there is a minimum occupancy floor.
Request the current GLA schedule from the landlord. Ask for the list of all spaces and their square footages used in the current year's denominator.
Sum the schedule. Add up all spaces included in the denominator. This should match the denominator figure in your reconciliation.
Reconcile against the lease exhibit. Compare the GLA schedule to the property's Exhibit A (tenant listing). Any space on the exhibit but not in the denominator requires a contractual basis for exclusion.
Verify your own square footage. Confirm that your leased square footage is correctly stated in the denominator calculation. An error in your own space, either too high or too low, directly affects your pro-rata share.
Check for anchor exclusion authorization. For any excluded anchor space, find the specific lease provision authorizing that exclusion. A landlord who excludes an anchor without explicit lease language is modifying the denominator without authorization.
If discrepancies exist, your audit rights clause gives you the right to inspect and copy the landlord's records. Document the discrepancy in writing and request a corrected reconciliation. If the overcharge is material, running a full CAM audit covering all open reconciliation years is worth doing before the audit rights window closes.
Legal Disclaimer: This article provides general educational information about gross leasable area definitions and CAM calculations in commercial leases. This is not legal advice. Consult qualified commercial real estate counsel before negotiating or signing any commercial lease.
Frequently Asked Questions
What is the difference between GLA and rentable square footage?
GLA (Gross Leasable Area) is used primarily in retail leases and measures space from exterior wall faces or demising wall centerlines, excluding common areas like corridors and courts. Rentable square footage is used in office leases and typically includes a load factor or add-on factor to allocate a share of floor common areas to each tenant's rentable area. The two measurements produce different numbers for the same physical space and are governed by different BOMA standards.
How does GLA affect CAM charges?
GLA is the denominator in your pro-rata CAM share calculation. Your share equals your space divided by GLA, times total CAM costs. When the reported GLA shrinks because of anchor exclusions or vacancy adjustments, your percentage share of the same cost pool increases. A 200,000 SF center with 80,000 SF of anchors excluded from the denominator charges inline tenants 67% more per square foot than they would pay against the full GLA denominator.
Can a landlord change the GLA after lease signing?
The GLA denominator is governed by your lease's definition. If the definition is specific and the landlord changes the denominator without a contractual basis, that is potentially a billing error or breach. Landlords can legitimately adjust the denominator for reasons authorized by the lease, such as adding new space through an expansion or adjusting for GLOA under a lease that uses occupied-only definitions. Track the reported denominator from each year's reconciliation and investigate unexplained changes.
What is GLOA and why does it matter for CAM?
GLOA stands for Gross Leasable Occupied Area, the subset of GLA that is actually leased and occupied. When a lease uses GLOA as the denominator, vacant space is excluded. This shifts the cost of vacancy from the landlord to the occupied tenants. A 10% vacancy in a center with a $1,000,000 CAM pool means occupied tenants absorb the full $1,000,000 rather than $900,000. Negotiate for GLA (full leasable area, including vacant space) rather than GLOA to keep the landlord responsible for their own vacancy.