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CamProof › Pro-rata share calculator

Pro-rata share calculator

Tenant RSF ÷ building area, or ÷ occupied area, or a fixed percentage from the lease — prorated by the days the tenant was in the space. See every tenant's share side by side.

🔒 Ledger & leases never leave your browser📒 QuickBooks · Yardi · AppFolio · Excel🧾 Statements that show the math🆓 Free, no signup

How it works

  1. Enter the building's rentable area and any area excluded from the denominator.
  2. Add tenants with RSF and lease dates (or import a rent roll CSV).
  3. Compare shares and the vacancy the landlord absorbs, then generate statements.

Why CamProof

For owners, bookkeepers and small property managers who reconcile CAM, taxes and insurance once a year — and would rather not rebuild the spreadsheet every time.

Starts from your books

Drop a QuickBooks Profit and Loss or transaction detail, or a Yardi, AppFolio or Buildium export. Map each account to a pool once; CamProof remembers it next year.

Real lease mechanics

Pro-rata by GLA, occupied area or fixed %, partial years by day, gross-up of variable costs, base years, expense stops, three kinds of caps, admin fees inside or outside the cap.

Statements tenants accept

One page per tenant with every step of the calculation, the building's expense detail, the balance or credit and the new monthly estimate. Print or save as PDF.

Catches mistakes first

Warnings for missing GLA, tenant areas larger than the building, shares over 100%, credits from reversed signs, caps without a basis and leases outside the period.

Landlord summary

See where every dollar went: billed, absorbed by vacancy, lost to base years and caps, and earned in admin fees — your recovery rate per pool.

Private by design

Rent rolls and ledgers are processed in your browser tab. No account, no upload, no connection to your accounting system. Save the project as a file you keep.

FAQ

How do I calculate pro-rata share?

Pro-rata share = tenant's rentable square feet ÷ the building's total rentable square feet. A 2,400 SF tenant in a 24,000 SF center has a 10% share. If the tenant was only open 7 months, multiply by days in occupancy ÷ days in the year.

What is an occupied-area denominator?

Some leases divide by the area actually leased rather than the whole building, so tenants also pay the vacant space's share. It's less common and usually negotiated — check your lease before using it.

Is my data uploaded?

No. Your ledger, tenants and lease terms are read and calculated by JavaScript running in your browser tab, and saved only in this browser (or in a project file you download). There's no account and no server copy.

What is a CAM reconciliation?

After the year ends, the landlord compares each tenant's actual share of common area maintenance (and, in NNN leases, taxes and insurance) with the monthly estimates the tenant paid, then bills the shortfall or credits the overpayment.

Which accounting exports work?

QuickBooks Online and Desktop Profit and Loss, General Ledger and Transaction Detail by Account reports, plus Yardi, AppFolio, Buildium, Rent Manager or any CSV/Excel file with account and amount columns. You can also type expenses in.

Does it replace reading the lease?

No. CamProof applies the terms you enter — shares, base years, stops, caps, gross-ups and fees — in the order most leases use. Your lease governs; review each statement before you send it.

What's free?

The full reconciliation on screen for any number of tenants, the landlord summary and all warnings, plus statements, CSV and Excel exports for properties with up to 3 tenants. Pro unlocks statements and exports for every tenant.

More CAM reconciliation tools & guides