NOI Net Operating Income

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Net Operating Income — NOI for short — is the profit a property generates before you factor in the mortgage, and it’s the number every…

Net Operating Income — NOI for short — is the profit a property generates before you factor in the mortgage, and it’s the number every serious investor calculates before making an offer.

The formula is dead simple: take all the income a property produces, then subtract all the operating expenses. Don’t include mortgage payments, income taxes, or capital expenditures. What’s left is your NOI.

The NOI Formula

Here’s how it works on a small apartment building:

  • Gross rental income: $96,000/year (8 units at $1,000/month)
  • Vacancy loss (7%): -$6,720
  • Other income (laundry, parking): +$3,600
  • Effective gross income: $92,880

Now subtract operating expenses:

  • Property taxes: $12,000
  • Insurance: $4,800
  • Maintenance/repairs: $7,200
  • Property management (8%): $7,430
  • Utilities (owner-paid): $6,000
  • Total operating expenses: $37,430

NOI = $92,880 – $37,430 = $55,450

Why NOI Matters

NOI is the foundation for almost every other investment metric. Divide the purchase price by NOI and you get the cap rate. Lenders use NOI to determine how much they’ll loan you through the debt service coverage ratio (DSCR). Appraisers use it to value commercial properties through the income approach.

It strips out financing — which varies from buyer to buyer — and shows the property’s raw earning power. An all-cash buyer and someone putting 20% down see the same NOI. That makes it the fairest way to compare two properties side by side.

Common NOI Mistakes

The biggest error? Using the seller’s expense numbers without questioning them. Sellers routinely understate expenses by self-managing (so no management fee appears), deferring maintenance, or lumping capital improvements into operating costs to inflate value.

Always rebuild the NOI from scratch. Call insurance agents for real quotes. Pull actual tax records. Budget 5-10% for vacancy even if the building is currently full. A “proforma NOI” is a fantasy — you want actual, trailing-12-month numbers wherever possible.

NOI and Property Valuation

For commercial real estate, NOI directly determines price. If the market cap rate is 6%, a property with $55,450 NOI is worth roughly $924,167. Boost that NOI by $10,000 through better management or rent increases, and the property value jumps by $166,667. That’s the power of forced appreciation.

Use our mortgage calculator to see how financing affects your returns after NOI. For a complete look at evaluating properties, visit our buying guide or explore more terms in the glossary.

Real-World Example

You own a 4-unit apartment building generating $72,000/year in gross rental income. Annual operating expenses: $7,200 property taxes, $3,600 insurance, $4,800 maintenance, $2,400 property management, $3,600 vacancy allowance (5%), and $1,200 miscellaneous. Total expenses: $22,800. NOI = $72,000 – $22,800 = $49,200. This NOI drives your cap rate (if the property cost $650,000, cap rate = 7.6%), your DSCR (if annual debt service is $38,400, DSCR = 1.28), and your property valuation for lenders. NOI excludes mortgage payments because it measures the property’s earning power independent of your financing.

Run the Numbers

Use our NOI calculator to see how noi (net operating income) applies to your specific situation. Plug in your numbers and compare scenarios before making any financial commitments.

Related Terms

Understanding noi (net operating income) connects to several other concepts: Cap Rate, Cash-on-Cash Return, DSCR, and Rental Yield. Each of these terms interacts with noi (net operating income) in ways that affect your buying power, monthly costs, or investment returns.

Frequently Asked Questions

Does NOI include mortgage payments?

No. NOI specifically excludes debt service (mortgage payments), capital expenditures, depreciation, and income taxes. It measures the property’s operating performance regardless of how it is financed. This lets investors and lenders compare properties on equal footing, whether they were bought with cash, a conventional loan, or seller financing.

What is a good NOI for rental property?

There is no universal benchmark because NOI depends on property type, size, and location. What matters is the NOI relative to the purchase price (cap rate) and to debt service (DSCR). A $50,000 NOI is great on a $600,000 property (8.3% cap) but mediocre on a $1.2 million one (4.2% cap). Focus on ratios, not raw numbers.