This worksheet vs. reconciling CAM by square footage alone
Tenant square footage divided by the building's total, times annual expenses, is the whole calculation — unless the lease lets the landlord gross up the occupancy-sensitive share of expenses to a stated target occupancy. Skip that clause and an under-occupied building's CAM bill comes out understated.
What square footage alone gets you
Area share times annual expenses is correct, exactly, whenever the building ran at or above the lease's gross-up target occupancy for the statement period, or the lease carries no gross-up clause at all. Most of the CAM math genuinely is that simple: one ratio, one multiplication, done.
It stops being the whole answer the moment both of two things are true: the lease has a gross-up clause, and the building ran under the target occupancy that clause names — typically 95%. In that case, only the occupancy-sensitive share of expenses (utilities, janitorial, and similar costs that track how full the building is) gets adjusted upward to what it would have cost at full target occupancy; fixed costs like a management fee or a roof reserve are never touched. Area share alone has no way to apply that adjustment, so it reconciles against the expenses as billed and quietly leaves the gross-up out.
What this worksheet adds
It takes the same five statement figures — annual expenses, total rentable area, tenant area, billed amount, and credits — and three optional gross-up fields: what share of expenses is variable, the building's actual occupancy for the period, and the lease's target occupancy. Leave the three blank and it reproduces the area-only figure exactly. Fill them in and it grosses up the variable share before applying the area ratio, and shows the dollar amount that adjustment added.
| Square footage alone | This worksheet |
|---|---|
| Applies the area ratio to expenses exactly as billed, with no way to account for a gross-up clause. | Grosses up the variable share of expenses to the lease's target occupancy before applying the area ratio, when the fields are filled in. |
| Gives one number regardless of how full the building actually was during the statement period. | Reports the dollar adjustment the gross-up added, so it can be checked against what the lease's own clause allows. |
| Has no way to flag that an under-occupied building understates the modeled share without the clause applied. | Shows the modeled share both ways, on request, from the same five base inputs. |
| Compares against a single billed figure with no record of the comparison. | Computes a variance against net billed and a share link that hands the same numbers to a landlord, tenant, or accountant. |
This tool needs no account and no sign-in: it runs entirely in your browser, and a share link carries only the numbers in the form — nothing is uploaded.
Same suite, one clause changes the number
Take this worksheet's own defaults: a 1,000 sq ft suite in a 10,000 sq ft building, $120,000 in annual CAM expenses. Read as pure square footage — 10.00% of the building — the modeled share is $12,000 a year, $1,000 a month. That is the whole answer if the building ran at or above target occupancy, or the lease has no gross-up clause.
Add a gross-up clause: 60% of expenses classed as variable, the building running at 75% actual occupancy against a 95% target. The variable share ($72,000) grosses up by a factor of 95 ÷ 75, adding $19,200 to the expense pool before the area ratio is applied. Effective annual expenses become $139,200, and the modeled tenant share rises to $13,920 a year, $1,160 a month — $1,920 a year more, 16% above the square-footage-only figure. Same suite, same total expenses, same area ratio. Only the occupancy clause changed the number.
Common questions
What's wrong with just using square footage share alone?
Nothing, if the building ran at or above the lease's gross-up target occupancy, or the lease has no gross-up clause at all -- area share times annual expenses is the whole calculation in that case. It goes wrong when the lease lets the landlord gross up the occupancy-sensitive share of expenses (utilities, janitorial -- costs that track how many suites are occupied) to what they would have cost at a stated target occupancy, usually 95%, and the building actually ran below that. Area share alone applies the ratio to the expenses as billed and never adjusts for the shortfall, which understates the modeled amount for a fully-tenanted year.
How much difference can the gross-up make in practice?
Using this worksheet's own defaults -- a 1,000 sq ft suite in a 10,000 sq ft building, $120,000 in annual CAM expenses -- square footage alone models the tenant's share at $12,000 a year, $1,000 a month. Add a gross-up clause with 60% of expenses classed as variable, the building running at 75% actual occupancy against a 95% target, and the modeled share rises to $13,920 a year, $1,160 a month -- $1,920 a year more, 16% above the area-only figure, from the same square footage and the same expense total.
How do I know if my lease has a gross-up clause?
Check the CAM or operating-expense reconciliation section of the lease itself for language about adjusting or grossing up expenses to a stated occupancy percentage. If that language is absent, area share alone is the correct calculation and this worksheet's optional gross-up fields should stay blank -- they default to a complete no-op (0% variable, 100% actual and target occupancy) so leaving them empty reproduces the area-only figure exactly.
Do I need my accountant's numbers to use this?
No. Five numbers already on the statement -- annual expenses, total rentable area, your tenant area, the billed amount, and any credits -- plus three optional gross-up fields if the lease has that clause. The worksheet does the area-share and gross-up arithmetic; nothing is uploaded, and a share link carries only the numbers you entered.
Open the CAM Reconciliation Check, or read how much CAM do you owe based on square footage? for the area-only arithmetic on its own.