What Is NOI (Net Operating Income)?
Net operating income is the backbone of commercial real estate valuation. Every cap rate, every DSCR calculation, and every cash flow projection starts here.
What is NOI in commercial real estate?
Net operating income (NOI) is the total annual income a commercial property generates after subtracting all operating expenses — but before debt service, capital expenditures, and income taxes. It measures the property’s operating performance independent of how it’s financed or who owns it.
NOI is the most fundamental number in commercial real estate. It drives cap rate calculations, determines how much a lender will lend (via DSCR), and anchors virtually every valuation and underwriting model. If you get NOI wrong, everything downstream is wrong.
The key distinction is what NOI includes and excludes. It includes all rental income and other property income (parking, storage, antenna leases). It subtracts operating expenses: property taxes, insurance, maintenance, management fees, and reserves. It does not include mortgage payments, depreciation, amortization, capital improvements, or tenant improvement costs.
How to calculate NOI
NOI = Gross Revenue − Operating Expenses
Gross revenue includes all rental income from tenants — base rent, percentage rent, CAM reimbursements (for NNN leases), and any other property income like parking fees or storage charges. For properties with vacancy, use effective gross income (gross potential rent minus vacancy and credit loss).
Operating expenses include property taxes, property insurance, common area maintenance (CAM), management fees (typically 3–6% of gross revenue), repairs and maintenance, utilities (if paid by landlord), and replacement reserves.
The critical rule: debt service is never included. Neither are capital expenditures, tenant improvements, leasing commissions, depreciation, or income taxes. These are treated separately in a full underwriting model because they vary by owner and financing structure, while NOI reflects the property’s intrinsic earning power.
Example: NOI calculation for an industrial property
Sample inputs
- Base rent (40,000 SF × $16/SF)
- $640,000
- CAM reimbursements
- $120,000
- Other income
- $15,000
- Gross revenue
- $775,000
- Property taxes
- $78,000
- Insurance
- $32,000
- CAM / maintenance
- $65,000
- Management (5%)
- $38,750
- Reserves
- $20,000
- Total expenses
- $233,750
Gross revenue of $775,000 minus total operating expenses of $233,750 gives a net operating income of $541,250. This is the number you’d use to calculate cap rate (NOI ÷ purchase price) and DSCR (NOI ÷ annual debt service).
Notice the operating expense ratio is about 30% — meaning 30 cents of every dollar of revenue goes to expenses, leaving 70 cents as NOI. For NNN industrial properties, this is typical. Gross lease office properties might have expense ratios of 40–50% or higher because the landlord covers more costs.
Why NOI matters for investors
NOI is the single number that determines property value in the income approach to valuation. Increase NOI and you increase value — it’s that direct. Every dollar of additional NOI translates to $12–$20 of additional value depending on the cap rate (at a 7% cap, each dollar of NOI is worth $14.29 in value).
This is why value-add investors obsess over NOI growth. Filling vacant space, pushing rents to market, reducing operating expenses, and adding ancillary income streams all flow directly to NOI — and therefore directly to property value and investor returns.
NOI also determines your borrowing capacity. Lenders use NOI to calculate DSCR (NOI ÷ annual debt service). If your NOI doesn’t cover the debt service by a sufficient margin (typically 1.20x–1.25x), you won’t get the loan. Underestimating NOI means underestimating your leverage capacity.
Common mistakes with NOI
Including debt service in expenses
The most common error. Debt service is not an operating expense — it depends on your financing, not the property's operations. NOI must be calculated before debt service.
Ignoring vacancy and credit loss
Using gross potential rent without deducting for vacancy and collection losses overstates your income. Even stabilized properties should assume 3–5% vacancy unless there's a long-term lease guarantee.
Excluding management fees
Even self-managed properties should include a management fee (typically 3–6%) for accurate NOI. If you sell the property, the new owner will likely hire management, and appraisers will include this cost regardless.
Confusing NOI with cash flow
NOI is before debt service and capital expenditures. Cash flow is after debt service. A property can have strong NOI and still produce negative cash flow if it's highly leveraged.
Using trailing vs. projected NOI inconsistently
Trailing NOI reflects actual past performance. Projected (pro forma) NOI includes assumptions about future rents, occupancy, and expenses. Make sure you're clear about which you're using — appraisers and lenders may treat them very differently.
Frequently asked questions
What does NOI stand for?
NOI stands for net operating income. It's the annual income a commercial property generates after operating expenses but before debt service, capital expenditures, and income taxes. It's the most important number in commercial real estate valuation.
Is NOI the same as profit?
No. NOI doesn't account for debt service (mortgage payments), capital expenditures, tenant improvements, leasing commissions, depreciation, or income taxes. It measures the property's operating performance — not the owner's after-tax profit or cash flow.
What expenses are included in NOI?
Operating expenses included in NOI are property taxes, property insurance, common area maintenance, management fees, repairs and maintenance, utilities (if landlord-paid), and replacement reserves. Capital expenditures, debt service, and tenant improvements are excluded.
How do you increase NOI?
Increase revenue (fill vacancies, raise rents to market, add ancillary income), decrease expenses (negotiate tax assessments, competitive bid insurance and service contracts, improve energy efficiency), or both. Every additional dollar of NOI directly increases property value.
What is the difference between NOI and cash flow?
NOI is income minus operating expenses — before debt service. Cash flow is NOI minus debt service (and sometimes minus capital reserves). A property can have strong NOI but negative cash flow if the debt service is high relative to income.
Final thoughts
NOI is where every commercial real estate analysis begins. Get it right and your cap rates, DSCR calculations, and cash flow projections are reliable. Get it wrong and you’re building your investment thesis on a bad foundation.
DealWise AI calculates in-place NOI automatically from your rent roll and operating expense inputs. No formulas to build, no line items to forget.
Related guides
What is cap rate?
How cap rate and NOI work together to determine value.
Cap rate vs NOI explained
The relationship between these two foundational metrics.
What is DSCR?
How NOI determines your debt service coverage ratio.
How to calculate DSCR
Step-by-step DSCR calculation with worked examples.
What is a good DSCR?
DSCR benchmarks by property type and lender.
CAM charges & gross-up
How recovery works per lease type, and the five things to check in a reconciliation.
Commercial lease types
NNN, gross, modified gross and full service — and who pays the operating expenses.
How to read an offering memorandum
Contractual, reported, asserted — and the cap rate trap that costs six figures.
What is a rent roll?
The document NOI is actually built from, lease by lease.
CapEx vs OpEx
What sits below the NOI line, and the capex line that lands in no year at all.
Calculators that run these numbers for you
NOI is never an input. It is what the rent roll adds up to.
DealWise AI derives NOI lease by lease — escalations, reimbursements, rollover and all — then carries it straight into cap rate, DSCR and the cash flow projection. Free to start.