Estimate common area maintenance charges and annual tenant pass-through costs.. Free online, browser-based tool with instant results and no signup.
Last updated: February 23, 2026
Total rentable area of the building
Your leased space within the building
HVAC, plumbing, elevator, general repairs
Grounds keeping, snow removal, etc.
Guards, cameras, access systems
Lobby, hallway, parking lot lighting
Building liability and property insurance
Property management company fees
Trash, pest control, miscellaneous
Typical: 5-15% on top of expenses
Common Area Maintenance (CAM) charges are the shared operating expenses that commercial tenants pay in addition to their base rent. They cover the costs of maintaining and operating the common areas of a building or shopping center, including lobbies, hallways, parking lots, landscaping, and shared utilities. Understanding CAM charges is critical for any business leasing commercial space because they can significantly impact your total occupancy cost.
CAM charges are typically allocated based on each tenant's pro-rata share, which is calculated by dividing the tenant's leased square footage by the total rentable square footage of the building. For example, if you lease 5,000 sqft in a 50,000 sqft building, your pro-rata share is 10%, and you would pay 10% of all eligible CAM expenses.
Pro-Rata Share = Tenant Sqft ÷ Building Sqft × 100
Many landlords also add an administrative markup of 5% to 15% on top of actual expenses to cover overhead and coordination costs. This markup is standard in the industry but should be clearly stated in your lease.
Most commercial leases require the landlord to provide an annual CAM reconciliation statement that compares estimated CAM charges paid during the year to actual expenses. As a tenant, you should review these statements carefully:
One of the most important lease negotiation points for commercial tenants is a CAM cap. A CAM cap limits how much your CAM charges can increase each year, typically to a fixed percentage such as 3% to 5% annually. Without a cap, your CAM charges could spike unpredictably due to major repairs, rising insurance premiums, or new expenses the landlord decides to include.
There are two common types of caps: a cumulative cap that limits total growth over the lease term, and a compounding cap that limits year-over-year increases. A cumulative cap provides better protection for tenants because unused cap room does not carry forward to future years. Always negotiate for a cap based on controllable expenses (excluding insurance and property taxes, which are harder for landlords to control) or a cap on the total CAM amount.
Estimate common area maintenance charges and annual tenant pass-through costs.. Free online, browser-based tool with instant results and no signup. This tool runs in-browser for fast results without account setup.
CAM (Common Area Maintenance) charges are fees tenants pay to cover the costs of maintaining shared spaces in a commercial property, including lobbies, parking lots, landscaping, security, and common utilities. They are typically calculated based on each tenant's pro-rata share of the building.
Pro-rata share is calculated by dividing your leased square footage by the total building square footage. For example, if you lease 2,000 sqft in a 20,000 sqft building, your pro-rata share is 10%, meaning you pay 10% of total building CAM expenses.
A CAM cap limits how much your CAM charges can increase each year, typically 3-5%. It protects you from unexpected expense spikes. Always try to negotiate a cumulative (not compounding) CAM cap in your lease, as compounding caps can result in significantly higher charges over time.
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