What is this tenant’s share, under each definition?

A tenant's pro-rata share is the fraction of the property's shared costs (CAM, property taxes, insurance) that one tenant pays. It is the tenant's rentable square feet divided by the area the lease names as the denominator. A 3,000 sq ft tenant in a 45,000 sq ft center has a share of 3,000 ÷ 45,000 = 6.67%, so on a $180,000 expense pool it pays $12,000. The same tenant divided by 36,000 sq ft of leased area is 8.33%, or $15,000. The number depends entirely on which denominator the lease uses, which is why this calculator shows all four side by side.

Gross leasable area (GLA) is every leasable square foot in the property whether or not it is leased. Leased or occupied area counts only the space under lease during the year. In a full building they are the same number. In a half-empty center they are far apart: a 3,000 sq ft tenant is 6.67% of 45,000 sq ft of GLA but 8.33% of 36,000 sq ft leased. That is why a tenant in a center with vacancies cares about the denominator: a leased-area definition raises its share every time a neighbor leaves, while a GLA definition holds it steady.

Anchor tenants (a grocery or department store) and pad or outparcel tenants (a bank or restaurant on its own parcel) often maintain their own premises and pay a fixed contribution to common costs instead of a pro-rata share. Their square feet are taken out of the denominator so the remaining tenants split what is left. That raises every in-line share: 3,000 ÷ (45,000 − 12,000) = 9.09% instead of 6.67%. When you exclude an anchor's area, also take the anchor's own contribution out of the pool, or the other tenants pay for costs the anchor already covered.

Under a GLA denominator the vacant space has a share of the costs that nobody pays, so the landlord absorbs it. Under a leased-area denominator the vacant space drops out of the division and the remaining tenants pick up its costs. On a $180,000 pool the example tenant pays $12,000 of GLA but $15,000 of leased area: $3,000 of vacancy cost moved from the landlord to this one tenant. Some leases get a similar result another way, by grossing up variable expenses to a stated occupancy; that is a different mechanism and this calculator does not apply it.

Usable square feet is the space inside the tenant's own walls. Rentable square feet is usable plus the tenant's slice of the building's common areas: lobbies, corridors, restrooms, mechanical rooms. The ratio between them is the load factor, often 1.10 to 1.20, so a 2,600 usable sq ft suite with a 15% load factor is 2,990 rentable. Office leases nearly always state the share as rentable area divided by the building's rentable area. Use the same basis on both sides of the division; a usable figure over a rentable denominator understates the share.

Many leases write the share as a number, such as 9.09%, worked out when the lease was signed. If the property has since been expanded, re-measured, or lost an anchor, that number may no longer match any current definition. Which controls depends on the lease: some say the stated percentage is an estimate and the formula governs, others fix it until the lease is amended, and many allow the landlord to adjust it when the areas change. Enter the stated share here to see which definition it was worked from; if it matches none, find out what areas it came from before you bill with it.

Look in two places. The basic lease information or definitions section near the front usually states the share as a percentage, under a heading like Tenant's Proportionate Share or Tenant's Percentage. The operating expense, additional rent, or common area maintenance section then defines how it is calculated: the denominator (GLA, leased area, or either less anchors), whether leased area is measured at year end or averaged by month, any measurement standard such as BOMA, and whether the landlord may re-measure. When the two disagree, the lease usually says which prevails.

No. It compares the share percentage and the dollars of one expense pool under four denominators, and that is all. Caps on controllable expenses, base-year or expense-stop leases, gross-ups of variable costs, administrative fees, and an excluded anchor's own contribution to the pool are separate steps. Once you know which definition the lease uses, the CAM reconciliation calculator takes that share through a year-over-year cap and the estimates the tenant already paid.