What is NOI in Real Estate? Net Operating Income Explained
Net Operating Income (NOI) is the annual income a property generates after all operating expenses are deducted but before mortgage payments and income taxes. It is the single most important metric for evaluating rental and investment properties because it measures the property's ability to generate cash flow independent of how it is financed.
The formula: NOI = Gross Rental Income - Vacancy Loss - Operating Expenses
What counts as income
Gross rental income includes all rent collected from tenants, plus any additional income the property generates: laundry machine revenue, parking fees, pet rent, storage unit fees, late fees, and application fees. These ancillary income sources can add 3% to 8% to gross income on multi-family properties.
What counts as an operating expense
Operating expenses are the recurring costs of running the property. They include:
- Property taxes: Typically the largest single expense, ranging from 1% to 3% of property value annually depending on the state and jurisdiction.
- Insurance: Landlord/investment property insurance, including liability coverage. Budget $1,000 to $2,500 per year for a single-family rental.
- Property management: If you use a manager, typically 8% to 10% of collected rent for single-family, 5% to 8% for multi-family. If you self-manage, some investors still include a management expense to reflect the true cost of their time.
- Maintenance and repairs: Routine maintenance (HVAC filters, landscaping, minor repairs). Budget 8% to 12% of gross rent, or $1 to $2 per square foot annually.
- Utilities: Only utilities paid by the landlord (water, sewer, trash in many multi-family situations). Utilities paid by tenants are not included.
- HOA fees: If applicable, the monthly or annual homeowners association dues.
- Advertising and leasing costs: Costs to find tenants: listing fees, showing costs, background check fees not passed to applicants.
What does NOT count as an operating expense
- Mortgage payments (principal and interest): NOI is before debt service. This is the most common mistake. Mortgage payments are financing costs, not operating costs. Different buyers finance differently, so including the mortgage would make the metric buyer-specific rather than property-specific.
- Capital expenditures (CapEx): Major improvements like a new roof, HVAC replacement, or kitchen remodel are not operating expenses. They are capital improvements that extend the useful life of the property. CapEx is tracked separately in a reserve fund, typically 5% to 10% of gross income.
- Income taxes: Your personal or business income tax liability is not an operating expense of the property.
- Depreciation: This is an accounting deduction, not a cash expense.
NOI calculation example
Gross annual rent: $21,600 ($1,800/month)
Other income (late fees, pet rent): $600
Gross income: $22,200
Vacancy allowance (5%): -$1,110
Effective gross income: $21,090
Operating expenses:
Property taxes: $3,600 | Insurance: $1,500 | Management (8%): $1,687 | Maintenance: $2,000 | Utilities (water/trash): $1,200
Total operating expenses: $9,987
NOI: $21,090 - $9,987 = $11,103
How NOI is used
Property valuation (income approach)
NOI divided by the market cap rate gives you the property's value under the income approach. With a NOI of $11,103 and a 7% cap rate, the property is worth $11,103 / 0.07 = $158,614 based on its income.
Cap rate calculation
If you know the purchase price and NOI, you can calculate the cap rate: NOI / Purchase Price = Cap Rate. A property purchased for $150,000 with $11,103 NOI has a cap rate of 7.4%. This tells you your unlevered return on investment.
Debt Service Coverage Ratio (DSCR)
Lenders use DSCR = NOI / Annual Debt Service to determine if the property generates enough income to cover the mortgage. Most lenders require a DSCR of 1.20 or higher, meaning the NOI must be at least 120% of the annual mortgage payment.
Increasing NOI
There are only two ways to increase NOI: increase income or decrease expenses. Income increases come from raising rents (to market rates or through value-add improvements), reducing vacancy (better marketing, longer lease terms), and adding ancillary income (laundry, parking, storage). Expense reductions come from negotiating better insurance rates, protesting property taxes, reducing utility costs (LED lighting, low-flow fixtures), and efficient maintenance management.
Related guides
- The Income Approach to Real Estate Valuation
- Passive Income from Real Estate
- NOI (Glossary)
- Debt Service Coverage Ratio (Glossary)
- Deal Run Comp Analysis
Related Articles
- Net Operating Income (NOI): Formula, Calculator & Examples
- Cap Rate Explained: Formula, Good Rates & How to Calculate
- The Income Approach to Real Estate Valuation Explained