What Is Net Operating Income (NOI)?

Net Operating Income (NOI) is a property's annual revenue minus its operating expenses, excluding debt service, depreciation, capital expenditures, and income taxes. It represents the actual cash a property generates from operations. Lenders use NOI to size loans, investors use it to value properties, and appraisers use it to set market values. Every commercial real estate metric that matters -- DSCR, cap rate, debt yield -- starts with NOI. Get it wrong, and every number downstream is wrong too.

The NOI Formula

The formula looks simple, but calculating each component correctly is where deals get won or lost. Here is the full waterfall.

Step 1: Potential Gross Income (PGI)

Start with the total rental income the property would generate if every unit or space were leased at market rates with zero vacancy. For multifamily, this is the sum of all unit rents at full occupancy. For office or retail, it is the total leasable square footage multiplied by the lease rate.

Step 2: Effective Gross Income (EGI)

Subtract expected vacancy and credit losses. Most underwriters use a vacancy rate between 5% and 10%, depending on the market and property type, though lenders may apply their own assumption regardless of actual occupancy.

Then add any ancillary income: parking fees, laundry revenue, vending, storage, late fees, pet rent, or application fees. This other income can be significant. A 200-unit apartment complex might generate $50,000 to $100,000 annually from non-rent sources.

Step 3: Operating Expenses

Subtract all recurring costs required to operate the property. Standard operating expense categories include:

• Property taxes
• Property insurance
• Property management fees (typically 3% to 8% of EGI)
• Maintenance and repairs
• Utilities (if owner-paid)
• Landscaping and snow removal
• Legal and accounting fees
• Advertising and marketing
• Reserves for replacement (typically $250 to $500 per unit per year for multifamily)

What NOI Excludes

These items are deliberately excluded from the NOI calculation because they are either financing-dependent, tax-dependent, or non-recurring:

• Debt service (mortgage principal and interest payments)
• Depreciation
• Income taxes
• Capital expenditures (roof replacements, HVAC systems, parking lot repaving)
• Leasing commissions
• Tenant improvement allowances

The reason for these exclusions is consistency. Two buyers can purchase the same property with completely different loan terms, tax situations, and capital plans. NOI strips all of that out so the property's operating performance can be compared on a level playing field.

NOI Worked Example

Consider a 50-unit apartment complex where each unit rents for $1,500 per month.

With an NOI of $599,800, you can now calculate every downstream metric. At a 5.5% cap rate, this property is worth roughly $10.9 million. Run your own numbers with the NOI calculator.

How Lenders Use NOI

NOI is the starting point for every commercial loan underwriting decision. Lenders take the NOI and run it through two primary tests.

DSCR Test

Debt Service Coverage Ratio divides NOI by annual debt service. Most lenders require at least 1.20x to 1.25x. Using the example above: if annual debt service is $450,000, the DSCR is 1.33x ($599,800 / $450,000), which clears most lender minimums. Use the DSCR calculator to test different loan scenarios.

Debt Yield Test

Debt yield divides NOI by the total loan amount. CMBS lenders typically want at least 10%. If the loan amount is $7 million, the debt yield is 8.6% ($599,800 / $7,000,000), which might not clear the threshold. The debt yield calculator can help you size the loan correctly.

NOI vs. Other Income Metrics

Common NOI Mistakes

Overstating NOI is the fastest way to kill a deal in underwriting. Lenders will catch it, and the borrower loses credibility. Watch for these recurring problems.

Including debt service in operating expenses. This is the most common error. Mortgage payments are not operating expenses. Including them deflates NOI artificially and confuses the analysis.

Using a zero-vacancy assumption. Even if a property is 100% occupied today, lenders will apply a vacancy factor, typically 5% to 10%. Presenting an NOI with no vacancy adjustment signals inexperience.

Ignoring reserves for replacement. Some owners do not set aside reserves for future capital items. Lenders will add this back in -- typically $250 to $500 per unit per year for multifamily -- which reduces the underwritten NOI below what the owner's financials show.

Mixing up trailing vs. pro forma NOI. Trailing NOI uses actual historical numbers. Pro forma NOI projects future performance, often assuming higher rents, lower vacancy, or completed renovations. Lenders primarily underwrite to trailing NOI unless there is strong evidence supporting the pro forma (signed leases, completed improvements). Know which number you are presenting and why.

Operating Expense Ratios by Property Type

Operating expenses as a percentage of EGI (the operating expense ratio) vary significantly by property type. These ranges give you a rough benchmark for whether a property's expenses look reasonable.

NNN (triple net) properties have the lowest operating expense ratios because tenants pay property taxes, insurance, and maintenance directly. Hospitality runs highest because hotels bear all operating costs plus staffing, food service, and amenities.

How NOI Drives Property Valuation

The income approach to commercial real estate valuation uses NOI as its foundation. The formula is straightforward:

Using our example: $599,800 NOI at a 5.5% cap rate puts the property value at approximately $10.9 million. At a 6.0% cap rate, the same property is worth $10.0 million. That half-point shift in cap rate changes the value by nearly $900,000. This is why accurate NOI matters so much -- small errors get amplified through the cap rate calculation. Run different scenarios with the cap rate calculator.

Increasing NOI

There are only two levers: increase income or reduce expenses. Strategies that move the needle include:

• Raising rents to market rates after lease expirations
• Reducing vacancy through better marketing or tenant retention programs
• Adding ancillary income (parking, storage, laundry, pet fees)
• Renegotiating service contracts (management, landscaping, cleaning)
• Appealing property tax assessments
• Submetering utilities to shift costs to tenants

Value-add investors specifically target properties with below-market rents or inflated expenses because the spread between current NOI and potential NOI represents their profit. A bridge loan is often used to finance the renovation period before stabilized NOI is achieved.

Frequently Asked Questions