Calculate your pro-rata share of common area maintenance charges in a commercial lease. Divide building CAM costs by tenant square footage.
Common Area Maintenance (CAM) charges are a major component of commercial lease costs. They cover the shared costs of maintaining the building's common areas: lobbies, parking lots, hallways, elevators, landscaping, snow removal, security, and management fees. Each tenant pays a pro-rata share based on their percentage of the building's total leasable area.
CAM charges typically range from $3–$10/sq ft annually for office space and $2–$6/sq ft for retail. These costs can vary significantly between buildings based on age, location, amenities, and management practices.
This calculator computes your pro-rata share of building CAM based on your unit size and the total building area. It also projects your annual and monthly CAM obligation so you can budget accurately.
Homebuyers, investors, and real-estate professionals all benefit from precise cam charges figures when evaluating properties, negotiating deals, or planning long-term investment strategies. Save this calculator and revisit it whenever market conditions or your financial situation changes.
CAM charges are often the biggest surprise in commercial leases. This calculator lets you verify the landlord's calculations and understand exactly what you're paying for. Instant recalculation lets you compare scenarios side by side, so every buying, selling, or investment decision is grounded in solid financial analysis. No sign-up is required, and you can instantly re-run scenarios as interest rates, property values, or your financial goals evolve. No sign-up is required, and you can instantly re-run scenarios as interest rates, property values, or your financial goals evolve.
Pro-Rata Share = Tenant Sq Ft / Total Building Sq Ft Annual CAM = Total Building CAM × Pro-Rata Share Monthly CAM = Annual CAM / 12 CAM per Sq Ft = Annual CAM / Tenant Sq Ft
Result: $16,500/year ($1,375/mo) — $5.50/sq ft
Your 3,000 sq ft unit in a 50,000 sq ft building gives you a 6% pro-rata share. With total building CAM of $275,000, your annual share is $16,500 ($1,375/month or $5.50/sq ft).
Class A office: $5–$10/sq ft. Class B office: $3–$7/sq ft. Strip retail: $2–$5/sq ft. Regional mall: $6–$12/sq ft. Industrial/warehouse: $1–$3/sq ft. If your CAM is significantly above these ranges, investigate the expense breakdown.
Key negotiation points: annual increase cap (5% is standard), exclusion of capital expenditures above a threshold ($10,000 is common), management fee cap (4% of gross rents), audit rights with defined timelines, and a right to year-end reconciliation within 90 days.
Some leases include an "administrative CAM" fee of 10–15% on top of actual CAM to cover the landlord's overhead. This is effectively double-dipping on management fees. Negotiate this out or cap it at a low percentage.
Common CAM items include: landscaping and snow removal, parking lot maintenance, elevator maintenance, common area utilities (lighting, HVAC), janitorial services, security, property management fees, common area repairs, and sometimes administrative costs. Always verify with current data, as conditions may change over time.
Your pro-rata share is your leased square footage divided by the total leasable area of the building (or property). For example, a 2,000 sq ft tenant in a 40,000 sq ft building has a 5% pro-rata share and pays 5% of total CAM costs.
Yes, CAM charges fluctuate annually based on actual expenses. Without a cap, they can increase significantly due to insurance hikes, new landscaping contracts, or major repairs. A 5–7% annual increase cap is a common negotiation point.
Each year, the landlord compares estimated CAM payments (billed monthly) against actual expenses. If you overpaid, you receive a credit. If you underpaid, you owe the difference. Reconciliation typically happens within 90–120 days of year-end.
Items that typically shouldn't be in CAM include: capital improvements (new roof, structural repairs), landlord's mortgage payments, tenant improvement costs for other tenants, legal fees for disputes, and costs covered by insurance claims. Consult a professional for advice tailored to your specific situation.
Most leases include an audit right allowing tenants to review the landlord's books. Exercise this right if charges seem high or increase unexpectedly. Some tenants hire professional lease auditors who work on a contingency basis (typically 25–50% of savings found).