What Is NOI in Real Estate? How to Calculate Net Operating Income

What Is Net Operating Income (NOI)?

Net operating income is the income a rental property generates from its operations after all ordinary operating expenses have been paid, but before any financing costs, income taxes, depreciation, or capital expenditures are considered. It is a property-level measure: it describes how the building itself performs as an operating business, not how a particular owner financed or taxes it.

Investors use NOI because it isolates operating performance from financing. That makes it possible to compare two properties on equal terms regardless of how each was purchased, and it is the input to two of the most common real-estate metrics — cap rate and debt service coverage ratio (DSCR).

NOI is not money the investor “takes home.” It is a before-financing operating figure. The cash an owner actually keeps after the mortgage is paid is cash flow, which is calculated separately from NOI. A property can show positive NOI and still produce negative cash flow when debt service is high.

The NOI Formula

NOI is built from two intermediate figures. First, potential rental income and other property income are reduced by vacancy and credit loss to produce effective gross income. Then operating expenses are subtracted to produce NOI.

How to Calculate NOI Step by Step

Work through the six steps below in order, keeping every figure in the same time frame (all monthly or all annual).

Step 1 — Calculate potential rental income

Start with the total rent the property could collect at full occupancy across all units. Use the rent the lease actually commands based on comparable leases, not an aspirational number. This is your potential rental income (also called gross scheduled income).

Step 2 — Add other property income

Add any other income the property produces — laundry, pet fees, late fees, parking, storage, or other legitimate ancillary income. The sum of potential rental income and other income is your gross scheduled income.

Step 3 — Estimate vacancy and credit loss

Subtract a vacancy and credit-loss allowance for turnover, downtime, and uncollected rent. A percentage of gross scheduled income is the simplest approach. The allowance should reflect realistic downtime for the local market, property type, and tenant turnover patterns — not an assumption of 100% occupancy forever.

Step 4 — Calculate effective gross income

Subtract vacancy and credit loss from gross scheduled income. The result is your effective gross income — the income the property realistically produces after normal downtime.

Effective Gross Income = Gross Scheduled Income − Vacancy / Credit Loss

Step 5 — Identify operating expenses

List every recurring cost of running the property — property taxes, insurance, management, routine maintenance and repairs, owner-paid utilities, HOA expenses where applicable, landscaping, pest control, common-area operating costs, and other ordinary recurring property operating expenses. The full list is covered in the next section and in our rental property operating expenses guide.

Step 6 — Subtract operating expenses

Subtract total operating expenses from effective gross income. The result is NOI — the property’s operating profit before financing.

NOI = Effective Gross Income − Operating Expenses

Mortgage payments are not in this step. NOI is financing-independent so you can compare properties on equal terms.

What Expenses Are Included in NOI?

Operating expenses are the recurring costs required to operate and maintain a rental property. The categories most rental properties carry include:

• Property taxes — the annual assessment, usually divided by 12 for a monthly budget.
• Property insurance — landlord (DP3) policy premiums.
• Property management — a percentage of collected rent when professionally managed, or a modeled allowance.
• Routine repairs and maintenance — the smaller, recurring upkeep that keeps the property operating.
• Owner-paid utilities — water, sewer, trash, or common-area electricity the landlord covers.
• HOA expenses — monthly dues and assessments where applicable.
• Landscaping — lawn care and seasonal upkeep where the owner is responsible.
• Pest control — recurring preventative service.
• Common-area operating costs — shared-area upkeep in multi-unit properties.
• Other ordinary recurring property operating expenses — licensing, advertising, legal, accounting, and similar recurring costs.

Actual expenses vary significantly by property type, age, condition, location, services, lease structure, and management strategy. Estimate each line from property-specific sources rather than generic national averages. For a complete walkthrough of each category, see our rental property operating expenses guide, and to itemize them on a real property, use the Rental Property Expense Calculator.

What Is NOT Included in NOI?

NOI generally excludes anything that depends on the owner’s financing structure, tax position, or capital investment decisions rather than the property’s ordinary operations. The items most commonly excluded are:

• Mortgage principal — repayment of loan balance is a financing event, not an operating cost.
• Mortgage interest / debt service — the cost of borrowing, subtracted after NOI for cash flow.
• Capital expenditures — major component replacements such as a roof or HVAC system.
• Depreciation — a non-cash accounting allocation, not an operating expense.
• Owner income taxes — personal tax liability belongs to the owner, not the property’s operations.
• Owner-specific financing costs — loan fees, points, and other costs tied to a particular financing arrangement.

This article does not provide tax advice. The treatment of repairs versus improvements, depreciation, and financing costs for tax purposes has specific rules — consult a qualified tax professional for your situation.

Does NOI Include Mortgage Payments?

No. Mortgage principal and interest (debt service) are financing costs, not property operating expenses, and they are not deducted when calculating NOI.

Financing depends on the investor’s capital structure — down payment, interest rate, loan term, and structure — not on the property’s operating performance. Keeping debt service below the NOI line is what lets you compare two properties on equal operating terms regardless of how each was purchased. The same property will show the same NOI under different loans but different cash flow.

NOI vs. Cash Flow

NOI and cash flow answer two different questions, and mixing them up is one of the most common analytical mistakes in rental investing.

NOI measures property operating performance before financing. It is effective gross income minus operating expenses, with no mortgage and no depreciation. Because financing is excluded, NOI lets you compare two properties on equal terms regardless of how each was purchased.

Cash flow reflects what remains after operating costs and debt service, subject to the assumptions used in your analysis. Cash flow is specific to your deal because it depends on your loan, your down payment, and your reserve policy.

A property can have positive NOI but negative cash flow at the same time — typically because high debt service consumes the operating income. That is why both numbers belong in any analysis. To run the full sequence on your own numbers, read How to Calculate Rental Property Cash Flow or use the Rental Property Cash Flow Calculator.

NOI vs. Gross Rental Income

Gross rental income is the total rent a property could collect — the top line before any costs. NOI is what remains after vacancy and operating expenses are accounted for. Rent collected is not NOI, because the property still has to be operated: taxes, insurance, management, maintenance, utilities, and other recurring costs all have to be paid out of that rent before you know what the property actually earns from operations.

Treating gross rent as NOI overstates the property’s operating performance by the full amount of vacancy and operating expenses — often hundreds of dollars per month. Gross rent tells you what comes in; NOI tells you what the property keeps from operations.

NOI vs. Profit

NOI should not automatically be called profit. Profit, in the everyday sense of money the owner keeps, depends on costs that NOI deliberately excludes — debt service, capital expenditures, depreciation, income taxes, and other owner-level costs. NOI is an operating measure that stops before any of those.

This is why a property can have positive NOI but negative cash flow at the same time. The building operates at a profit on paper, but once the mortgage payment is subtracted the owner is putting cash in to keep it running. Calling NOI “profit” hides that gap and can make a heavily financed deal look healthier than it is.

Rental Property NOI Example

The following hypothetical example walks through every line of an NOI calculation. The numbers are illustrative only.

Hypothetical example — educational purposes only.

Income assumptions (monthly)

Operating expenses (monthly)

Monthly NOI

Annual figures

Vacancy is deducted once, as a reduction to income — it is not also listed as an operating expense, so it is not double-counted. Mortgage payments and actual capital expenditures are not included here at all; debt service is subtracted from NOI later when calculating cash flow.

How NOI Is Used to Calculate Cap Rate

Cap rate expresses a property’s unlevered operating return as a percentage of its value or purchase price. NOI is the numerator:

Cap Rate = Annual NOI ÷ Property Value × 100

For a given property value, a higher NOI produces a higher cap rate, and a lower NOI produces a lower cap rate. Cap rate is one way to compare the unlevered operating return of different properties or to gauge how a property is priced relative to the income it produces.

No particular cap rate is universally “good.” A cap rate that makes sense in one market, price range, or risk profile may be unworkable in another. Acceptable returns depend on purchase price, financing, market, property condition, expected repairs, risk, investor objectives, and alternative opportunities available to you.

How NOI Is Used in DSCR

Debt service coverage ratio (DSCR) compares a property’s NOI to its debt service. It indicates the relationship between the operating income the property produces and the mortgage payments it must cover:

DSCR = NOI ÷ Debt Service

A DSCR above 1.0 means NOI exceeds debt service; a DSCR below 1.0 means debt service exceeds NOI. Lenders often use DSCR as one factor in underwriting a loan, because it reflects whether the property’s operations can support its financing.

Specific DSCR requirements vary by lender, loan program, property type, and deal. There is no universal threshold, and this article does not claim one. Treat DSCR as one input among several when evaluating how a property’s operations relate to its financing.

How to Improve Rental Property NOI

Because NOI equals effective gross income minus operating expenses, you can raise it by increasing income, reducing avoidable operating costs, or both. Possible strategies include:

• Reducing avoidable operating expenses — reviewing recurring service contracts and trimming costs that do not protect value or operations.
• Improving preventative maintenance — catching small issues before they become expensive repairs.
• Reviewing owner-paid utilities — confirming the landlord is not paying for tenant usage that could be metered separately.
• Reducing unnecessary turnover — retaining good tenants lowers vacancy and make-ready costs.
• Improving management efficiency — whether self-managed or professional, tighter processes reduce waste and downtime.
• Adding legitimate ancillary income — pet fees, laundry, parking, or storage where the property and lease support it.
• Improving occupancy — shorter turnover cycles and realistic marketing reduce lost rent.
• Reviewing rent relative to market and applicable laws — where rent sits below market and lease terms and local law allow, adjusting rent can raise income.

These are possible strategies, not guaranteed outcomes. Results depend on the property, market, lease terms, local law, and execution. Some actions — particularly rent changes — are constrained by lease terms and applicable law, so verify what is permitted before acting.

Common NOI Calculation Mistakes

• Using gross rent instead of effective income. Starting from rent collected skips vacancy and overstates NOI.
• Ignoring vacancy. Assuming 100% occupancy hides one of the largest recurring realities of operating a rental.
• Including mortgage payments. Debt service is a financing cost, subtracted after NOI for cash flow.
• Confusing CapEx with operating expenses. A new roof is a capital expenditure, not an ordinary recurring operating cost.
• Ignoring management. Even self-managers should consider a management allowance so the property’s economics stand on their own.
• Double-counting vacancy. Listing vacancy both as an income reduction and as an operating expense deducts it twice.
• Using annual expenses as monthly. Mixing time frames in one calculation produces wrong results. Pick one frame and convert everything to it.
• Ignoring utilities. Water, sewer, trash, and common-area electricity the landlord covers are easy to overlook.
• Confusing NOI with cash flow. NOI excludes debt service; cash flow includes it. Reporting one when someone asks about the other misleads.
• Calling NOI profit. NOI stops before financing, CapEx, depreciation, and taxes — it is not money the owner keeps.
• Using unrealistic income assumptions. Aspirational rent or 100% occupancy inflates NOI and every metric that depends on it.

Frequently Asked Questions