Net Operating Income (NOI): The Core Income Measure for Property Operations

Net operating income (NOI) is the income an investment property generates after operating expenses are subtracted, but before financing costs and income taxes are deducted.

For real-estate investors, NOI is one of the most important operating metrics because it isolates the property’s core earning power.

Basic Formula

The formula looks simple, but the real skill is understanding what belongs in each part.

What NOI Includes

NOI usually starts with property income such as:

• rent

• parking fees

• laundry or amenity income

• other recurring property-related revenue

Then it subtracts operating expenses such as:

• property management

• repairs and maintenance

• insurance

• utilities

• property taxes

What NOI Excludes

NOI usually excludes:

• mortgage interest

• principal payments

• income taxes

• major capital expenditures

That exclusion is important because NOI is meant to evaluate the property itself, not the investor’s financing decision.

Worked Example

Suppose a small apartment building produces:

• gross rental and other operating income: $250,000

• operating expenses: $95,000

Then:

That $155,000 is the income stream that can then be used in metrics such as capitalization rate (cap rate).

Why NOI Matters

NOI matters because it helps investors compare properties on an operating basis.

It is central to:

• property valuation

• lender underwriting

• acquisition screening

• portfolio performance tracking

A property with rising rents but badly rising expenses may look strong from the top line, yet have weakening NOI.

NOI vs. Cash Flow

NOI is not the same as investor cash flow.

• NOI measures the property’s operating performance before debt and taxes.

• Cash flow depends on the investor’s financing, tax situation, and capital spending decisions.

This is why two investors can own similar buildings with similar NOI but very different cash-on-cash return.

Related Terms

• Capitalization Rate (Cap Rate): Cap rate turns NOI into a valuation metric.

• Cash-on-Cash Return: Cash-on-cash return adds financing and cash investment structure.

• Gross Rent Multiplier (GRM): GRM values property more roughly because it ignores expenses.

• EBITDA: EBITDA is a broader business-performance concept that resembles NOI in spirit but is used in different contexts.

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