Investor BlueprintSelf-storage underwriting
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Sheet C-03CalculatorRev.

Self-storage NOI and expense ratio calculator

Build net operating income the way an underwriter does: potential rent, less vacancy and collection loss, plus ancillary income, less operating expenses.

01Rent roll summaryMonthly rent
Per occupied unit, per month
02Other income & lossAnnual
Concessions & bad debt
03Operating expensesAnnual
Operating expenses ÷ effective gross income
Net operating incomeAnnual
$293,302
64.0% NOI margin · $6.11 per SF
Gross potential rent$524,160
Vacancy−$78,624
Other income$24,500
Collection loss−$11,751
Effective gross income$458,285
Operating expenses (36%)−$164,983
NOI$293,302
Expense ratio
36.0%
Physical occ.
85.0%
Economic occ.
82.8%Collected ÷ potential rent
Opex per SF
$3.44

Carry this P&L forward. In Storage Underwriter the same line items roll into stabilization, with the post-sale tax bill, and on through a full projection.

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How it works

How self-storage NOI is built

Gross potential rent − Vacancy = Scheduled rent + Other income (tenant protection, fees, retail, truck) − Collection loss (concessions, bad debt) = Effective gross income (EGI) − Operating expenses = Net operating income (NOI)

The calculator follows the same statement structure as the Storage Underwriter app. Gross potential rent here is every unit at the average in-place rent. Collection loss is a percentage of scheduled rent plus other income.

Expense ratio vs. line items

Expense ratio is the fast screen: operating expenses as a share of EGI. It is useful when all you have is an offering memo. Its weakness is that it hides the lines that differ from facility to facility: property tax, payroll and insurance.

Line items are the real underwrite. Percentage lines such as a management fee or card processing fees are calculated on EGI. Everything else is an annual dollar amount. When you underwrite a purchase, replace the seller's lines with yours:

  • Management fee: include a third-party fee even if the seller self-manages.
  • Payroll: an owner working the counter for free is a cost you will pay.
  • Property tax: use the post-sale estimate, not the seller's bill.
  • Insurance: get a quote; don't roll forward the seller's policy.
  • Personal items: remove owner vehicles, phones and similar costs run through the business.

Using expense benchmarks carefully

Published margins are easy to misread. Public Storage reported a same-store direct NOI margin of 78.2% for 2025, but that figure is before indirect costs such as supervisory payroll and centralized management. A small facility paying its own manager, a management company and a local tax bill will carry a meaningfully higher expense load. Treat any single “normal” ratio as a sanity check, not an input.

36% ratioLine items
Effective gross income$458,285$458,285
Operating expenses$164,983$188,197
NOI$293,302$270,088
Expense ratio36.0%41.1%
Hypothetical 420-unit facility at 85% occupancy, $104 average rent; quick 36% ratio vs. line items.

In this example the line items, which include a 6% management fee and a full payroll, come in about $23,200 above the quick ratio. At a 6.5% cap that gap is worth about $357,000 of price. Reading the T12 and rent roll shows how to rebuild each line from the seller's documents.

Results are estimates based entirely on the figures you enter. They are not investment, lending, tax or legal advice.

FAQ

Questions

How do you calculate NOI for a self-storage facility?

Start with gross potential rent (every unit at its rent for twelve months), subtract vacancy to get scheduled rent, add ancillary income such as tenant protection, fees and retail, subtract concessions and bad debt to get effective gross income, then subtract operating expenses. Debt service, depreciation, income taxes and capital improvements are not operating expenses.

What is a normal expense ratio for self storage?

It varies widely with size, staffing, taxes and who manages the facility. Large REIT-operated facilities report very high NOI margins, but their reported margins can exclude centralized costs, so they are not comparable with a small facility's full P&L. Rebuild expenses line by line from the T12 and bills, and include a market management fee even if the seller manages the facility.

Should I include a management fee if I will self-manage?

Yes, for underwriting and valuation. A buyer or lender will assume the facility needs management, so NOI without a management fee overstates value. If you manage it yourself, the fee is compensation for your time.

Is property tax an operating expense?

Yes. It is usually one of the largest lines, and it may increase after a sale if the property is reassessed. Model the post-sale bill in the Deal Analyzer or the cap rate calculator.

What is the difference between NOI and cash flow?

NOI is before debt service and capital expenditures. Cash flow is what remains after paying the loan (and, in stricter definitions, after capital reserves). Two buyers with different financing see the same NOI but different cash flow.

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