How to Calculate CAM Charges
Step-by-step formula, worked examples, and common errors — for landlords, property controllers, and asset managers.
To calculate CAM charges: (1) identify total recoverable operating expenses for the property, (2) apply gross-up to variable expenses if occupancy is below the lease threshold, (3) multiply the expense pool by the tenant's pro-rata share (tenant SF ÷ denominator SF), (4) apply any CAM cap from the lease, and (5) subtract the tenant's estimated payments to get the true-up amount owed.
The CAM Charge Formula
Key Variables Defined
| Variable | Definition | Where to Find It |
|---|---|---|
| Total Recoverable Expenses | All operating costs the landlord can pass through to tenants, net of exclusions | GL report, filtered by recoverable expense codes |
| Tenant RSF | Rentable square footage leased by the tenant | Lease agreement, BOMA measurement |
| Denominator RSF | Building-wide SF used as the base for pro-rata math | Lease definition (total rentable area, total leasable area, or fixed number) |
| Gross-Up Threshold | The occupancy % at which variable expenses are normalized (typically 90–95%) | Lease clause (gross-up provision) |
| Actual Occupancy % | Actual leased SF ÷ total leasable SF during the period | Leasing schedule or rent roll |
| CAM Cap % | Maximum allowable year-over-year increase in tenant CAM obligation | Lease clause (escalation cap) |
| Estimated Payments | Monthly CAM payments already collected from tenant during the year | Accounts receivable / rent roll |
Step-by-Step Calculation Process
Determine total recoverable CAM expenses
Start with your GL report for the reconciliation year. Sum all operating expense line items that are recoverable under the lease. Remove any non-recoverable exclusions defined in the lease (capital improvements, financing costs, management fees above the cap, etc.). The result is your Total Recoverable Expense Pool.
Apply gross-up if occupancy is below the threshold
Most NNN leases require variable expenses to be grossed up to a threshold (usually 90% or 95%) when actual occupancy falls below that level. Fixed expenses (like property taxes and insurance) are not grossed up.
Use the CAM Gross-Up Calculator to model multiple occupancy scenarios side by side.
Calculate the tenant's pro-rata share percentage
Divide the tenant's leased RSF by the denominator defined in the lease. The denominator matters — verify whether it's total rentable area (TRA), total leasable area (TLA), or a fixed number. Anchor exclusions can also reduce the denominator.
Calculate tenant's gross CAM obligation
Apply CAM cap if applicable
If the lease has a CAM cap, calculate the maximum allowable obligation based on the cap structure. Non-cumulative caps reset each year; cumulative caps bank unused capacity.
Subtract estimated payments — calculate the true-up
Common CAM Calculation Errors
Three CAM Calculation Methods Compared
| Method | How It Works | Common In | Reconciliation Required? |
|---|---|---|---|
| Pro-Rata (Traditional) | Actual expenses × tenant SF ÷ denominator SF | NNN, NN leases | Yes — annual true-up |
| Fixed CAM ($/SF) | Flat rate per SF with annual escalator (e.g., 3% per year) | Retail, net leases | No — locked in |
| Base Year / Expense Stop | Tenant pays expenses above a base year or fixed stop amount | Full-service, gross leases | Yes — reconcile excess |
Use the Fixed CAM vs. Traditional Modeler to compare recovery under each method over a 3–5 year lease term.
Free Calculators for Each Step
Frequently Asked Questions
What is the formula for calculating CAM charges?
The basic formula: Tenant CAM = Total Recoverable Expenses × (Tenant RSF ÷ Denominator RSF). For leases with gross-up, variable expenses are first adjusted upward to the occupancy threshold before applying the pro-rata percentage.
How do you calculate a tenant's pro-rata share for CAM?
Divide the tenant's leased square footage by the building's total denominator square footage as defined in the lease. For example, if a tenant leases 5,000 SF in a 50,000 SF building, their pro-rata share is 10%. The denominator definition varies by lease — verify whether it's total rentable area, total leasable area, or a fixed number.
What is gross-up in a CAM calculation?
Gross-up adjusts variable operating expenses to what they would be at a defined occupancy threshold — typically 90% or 95% — regardless of actual occupancy. If a building is 80% occupied, variable expenses are divided by 0.80 and multiplied by 0.95 to normalize to 95%. This prevents tenants from underpaying when there are vacancies in the building.
What expenses are excluded from CAM calculations?
Common exclusions include: capital improvements (unless amortized per lease terms), financing costs and mortgage interest, leasing commissions and tenant improvement allowances, income taxes, depreciation, management fees above the contractual cap, and costs specific to other tenants. Always verify the specific exclusion language in each lease.
How does a CAM cap affect the calculation?
A CAM cap limits year-over-year increases in tenant CAM obligations. A 5% non-cumulative cap means the tenant's contribution cannot increase more than 5% over the prior year. A cumulative cap allows unused cap capacity to bank forward — if expenses only grew 2% one year, the landlord may be able to recover up to 8% in a subsequent year.
What is the difference between fixed and variable CAM charges?
Fixed CAM charges are set at a flat dollar or per-SF amount for the lease term, with only CPI or flat annual escalators — no annual reconciliation required. Variable (traditional) CAM charges are based on actual building operating expenses and require annual reconciliation where tenants true-up against actual costs.
Related Resources
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