Net Operating Income (NOI) Calculator
Calculate Net Operating Income for commercial real estate by subtracting operating expenses from gross rental income. Includes vacancy and credit loss, CAM, management, and reserves for a true cash-flow-before-debt-service figure.
Income
Commercial vacancy typically runs 5-10% depending on market and tenant credit.
Operating Expenses (exclude debt service & capex)
NOI Analysis
Enter income and expenses and click calculate.
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Introduction
Net Operating Income is the single number that every commercial real estate decision runs through. It sets the cap rate, the debt coverage ratio, the lender loan sizing, and the investor return, and it is the first line a buyer scrutinizes on a rent roll. The mistake most people make is including items that do not belong: debt service, depreciation, capital expenditures, and one-time leasing commissions all get stuffed into NOI by accident, and each one distorts the value of the property. The National Council of Real Estate Investment Fiduciaries and standard appraisal practice define NOI as effective gross income minus operating expenses, before debt service and before capex. This calculator builds NOI the way a lender and an appraiser build it, so your cap rate and DCR downstream are built on the right base.
What This Calculator Does
This tool calculates Net Operating Income for a commercial property from gross rental income, other income, vacancy and credit loss, and a full operating expense line. It subtracts property tax, insurance, utilities, repairs and maintenance, management fees, CAM, replacement reserves, and other opex from effective gross income to produce NOI. It also reports NOI per square foot, the operating expense ratio, and an implied cap rate from a market value input so you can see how the income translates to value.
The Formula
Potential Gross Income is all scheduled rent plus other income (parking, late fees, laundry, signage). Vacancy and credit loss is the expected uncollected portion, typically 5% to 10% for commercial depending on tenant credit and market. Effective Gross Income is what you actually expect to collect. Operating expenses are the costs to run the property: property tax, insurance, utilities, repairs and maintenance, management, CAM, and replacement reserves. NOI excludes debt service (it is a financing cost, not an operating cost), depreciation (a non-cash accounting item), capital expenditures (lumpy, not operating), and leasing commissions (one-time). The operating expense ratio typically runs 30% to 45% of EGI for office and retail and 25% to 35% for multifamily.
Step-by-Step Example
Enter income
A 12,000 sq ft retail strip with $480,000 of annual rent and $24,000 of parking and signage income.
Set vacancy
She enters 7% vacancy and credit loss, typical for the submarket tenant mix.
Enter operating expenses
Property tax $42,000, insurance $18,000, utilities $22,000, maintenance $15,000, management $28,000, CAM $9,000, reserves $12,000, other $5,000.
Read NOI and cap rate
EGI is about $469,680, opex is $151,000, NOI is about $318,680. At a $5,200,000 value that is a 6.13% cap rate.
Real-World Use Cases
Acquisition Underwriting
A buyer builds NOI from the trailing 12-month operating statement to verify the seller pro forma before bidding, since inflated NOI is the most common deal pricing trick.
Lender Loan Sizing
A commercial lender uses NOI to size the loan via the debt coverage ratio, since the maximum loan is NOI divided by target DCR divided by annual debt service per dollar.
Annual Budgeting and Variance
A property manager builds the year-ahead NOI budget and tracks actuals against it monthly to catch expense creep before it erodes the distribution.
Common Mistakes to Avoid
Including debt service in operating expenses. Debt service is a financing cost, not an operating cost. Including it understates NOI and makes the cap rate and DCR wrong. Lenders and appraisers will reject a pro forma that mixes the two.
Including capital expenditures in opex. A new roof or HVAC replacement is a capital expenditure, not a recurring operating expense. Use a replacement reserve (a small annual accrual) instead, so NOI reflects the steady-state cost.
Underestimating vacancy and credit loss. A 100% occupied building is not 0% vacancy. Use a market vacancy rate (5% to 10%) plus a credit-loss assumption for tenant default, or you will overvalue the property.
Forgetting replacement reserves. Lenders require a reserve (often $0.20 to $0.30 per sq ft annually for commercial) to cover future capital needs. Omitting it overstates NOI and can fail lender underwriting.
Frequently Asked Questions
Is NOI before or after debt service?
NOI is before debt service. It measures the property operating performance independent of how it is financed. Cash flow after debt service is called cash flow after debt service or levered cash flow, and it is NOI minus annual debt service. Mixing the two is the most common pro forma error.
What is a good operating expense ratio for commercial property?
Office and retail typically run 30% to 45% of effective gross income, depending on the lease structure (NNN leases push expenses to the tenant and lower the ratio for the landlord). Multifamily runs 25% to 35%. A ratio above 50% usually signals an expense problem or an under-rented property.
Does NOI include depreciation?
No. Depreciation is a non-cash accounting deduction used for tax purposes, not an operating expense. NOI is a cash-based operating measure. Including depreciation would understate the property cash flow and distort the cap rate.
How is NOI used to calculate cap rate?
Cap rate = NOI / property value. If a property generates $318,680 of NOI and sells for $5,200,000, the cap rate is 6.13%. Investors and appraisers also work backward: target value = NOI / target cap rate. The accuracy of the cap rate depends entirely on the accuracy of the NOI.
Accuracy and Disclaimer
This calculator builds NOI using standard commercial real estate definitions (effective gross income minus operating expenses, before debt service and capex). It does not account for lease-specific recoveries, tenant improvements, leasing commissions, or market-specific expense stops. NOI varies by market, asset type, and lease structure. This is not investment advice or an appraisal. Consult a licensed commercial broker or appraiser for property-specific valuation.
Conclusion
NOI is the foundation for every downstream commercial metric, so getting it right matters more than any other number on your pro forma. Build it here, then take the result into our Commercial Mortgage DCR Calculator for loan sizing and the Cap Rate Calculator for valuation.
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