How to Use This Calculator
- 1
Enter Monthly Rent per Unit
Input the average monthly rent charged per unit in your rental property.
- 2
Enter Number of Units
Input the total number of rental units in the property.
- 3
Set Other Monthly Income
Enter any additional monthly income from parking, laundry, storage, or pet fees.
- 4
Set Vacancy Rate
Enter the expected vacancy rate as a percentage of gross income — typically 5-10% for most markets.
- 5
Enter Operating Expenses
Input annual operating expenses: property tax, insurance, maintenance, and management fees. Optionally expand advanced options to add utilities and other expenses.
- 6
Review your results
The calculator displays Net Operating Income (NOI), Monthly NOI, Effective Gross Income, NOI Margin, and Implied Value at a 6% cap rate. The insights panel shows your expense ratio, per-unit NOI, and vacancy impact.
Example Calculation
A landlord with a 4-unit property renting at $2,500/month per unit, $200/month other income, and 5% vacancy wants to calculate NOI.
Monthly Rent per Unit
$2,500
Number of Units
4
Other Monthly Income
$200
Vacancy Rate
5%
Property Tax
$3,600/yr
Insurance
$1,800/yr
Maintenance & Repairs
$2,400/yr
Property Management
$1,200/yr
Results
Net Operating Income (NOI)
$105,480
Monthly NOI
$8,790
Effective Gross Income
$116,280
NOI Margin
90.7%
Implied Value (6% Cap)
$1,758,000
Tips
Reduce Vacancy to Boost NOI
On this example property, reducing vacancy from 5% to 3% adds $2,448 annually to NOI. Competitive pricing, responsive maintenance, and good tenant screening all help reduce vacancy.
Track Expenses as a Percentage of Income
A healthy expense ratio for multifamily is typically 35-50% of effective gross income. If your ratio exceeds 50%, review maintenance, management, and utility costs for potential savings.
Use NOI to Compare Properties
NOI is the single best metric for comparing rental property profitability because it excludes financing costs (which vary by buyer). A $105,480 NOI at a 6% cap rate implies an $1,758,000 property value.
Include All Operating Expenses
Don't forget to include utilities (if landlord-paid), landscaping, pest control, legal, and accounting costs. Expand the advanced options to add these so your NOI calculation is accurate.
Understanding NOI: The Net Operating Income Calculator
The NOI Calculator helps real estate investors and property managers evaluate the profitability of rental properties by calculating Net Operating Income — the annual income remaining after all operating expenses are deducted from effective gross income. NOI is the foundation metric for property valuation, cap rate analysis, and comparing investment opportunities.
For a 4-unit property renting at $2,500 per month per unit with $200 monthly other income, a 5% vacancy allowance, and $10,800 in annual operating expenses, the NOI is $105,480 — implying a property value of $1,758,000 at a 6% cap rate.
The NOI Formula
The NOI Calculator uses straightforward income-minus-expenses logic with a vacancy adjustment:
Gross Income = (Monthly Rent x Units x 12) + (Other Monthly Income x 12)
Vacancy Loss = Gross Income x Vacancy Rate
Effective Gross Income = Gross Income - Vacancy Loss
NOI = Effective Gross Income - Total Operating Expenses
Additional derived metrics:
NOI Margin = (NOI / Effective Gross Income) x 100
Expense Ratio = (Total Expenses / Effective Gross Income) x 100
Implied Property Value = NOI / Cap Rate
Worked Example: Calculating NOI for a 4-Unit Property
Consider a landlord with the following property details:
- Monthly Rent per Unit: $2,500
- Number of Units: 4
- Other Monthly Income: $200
- Vacancy Rate: 5%
- Annual Expenses: Property Tax $3,600 + Insurance $1,800 + Maintenance $2,400 + Management $1,200 + Utilities $1,200 + Other $600 = $10,800
- Calculate Gross Income:
Gross Rent = $2,500 x 4 x 12 = $120,000Other Income = $200 x 12 = $2,400Gross Income = $120,000 + $2,400 = $122,400
- Calculate Vacancy Loss:
Vacancy Loss = $122,400 x 5% = $6,120
- Calculate Effective Gross Income:
EGI = $122,400 - $6,120 = $116,280
- Calculate NOI:
NOI = $116,280 - $10,800 = $105,480
- Calculate Implied Value:
Property Value = $105,480 / 0.06 = $1,758,000
The property generates $105,480 in annual NOI ($8,790 per month), with a strong 90.7% NOI margin and each unit contributing $26,370 annually.
Why NOI Matters for Real Estate Investors
NOI is the single most important metric in commercial and investment real estate because it represents the property's earning power independent of how it's financed. Since NOI excludes mortgage payments, every buyer can objectively compare properties using this number. Lenders also rely heavily on NOI to determine debt service coverage ratios (DSCR) when underwriting investment property loans.
In 2026, with interest rates and property values in flux, understanding your property's NOI helps you make informed decisions about buying, selling, or refinancing. A property with strong, stable NOI will maintain its value even in uncertain markets.
Common Mistakes in NOI Calculations
The most common mistake investors make is underestimating operating expenses. Many new investors forget to include reserves for maintenance, property management fees (even if self-managing — your time has value), and landlord-paid utilities. Another frequent error is using an unrealistically low vacancy rate.
Additionally, NOI should not include capital expenditures (CapEx) like roof replacements or major renovations. These are separate from operating expenses and are typically budgeted separately. Mixing CapEx into NOI distorts the property's true operating performance.
Frequently Asked Questions
What is Net Operating Income (NOI)?
Net Operating Income (NOI) is the total annual income a property generates after subtracting all operating expenses, but before mortgage payments, capital expenditures, and income taxes. It's the primary metric used by real estate investors to evaluate a property's profitability and determine its value using the capitalization rate (cap rate) formula.
What expenses are excluded from NOI?
NOI excludes mortgage payments (debt service), capital expenditures (major improvements like a new roof), income taxes, and depreciation. It only includes operating expenses like property tax, insurance, maintenance, management fees, and utilities. This makes NOI useful for comparing properties regardless of their financing structure.
What is a good NOI margin?
A good NOI margin varies by property type. For multifamily residential properties, an NOI margin of 50-65% of effective gross income is typical. Single-family rentals often have lower margins (40-55%) due to higher per-unit expenses. An NOI margin above 65% is excellent, while below 40% suggests high expense burden or low rents relative to costs.
How does cap rate relate to NOI?
Cap rate (capitalization rate) relates NOI to property value through the formula: Property Value = NOI / Cap Rate. A lower cap rate implies higher property value for the same NOI (common in competitive markets), while a higher cap rate implies lower value (higher-risk markets). For example, $105,480 NOI at a 6% cap rate implies $1,758,000 property value, but at an 8% cap rate the same NOI implies only $1,318,500.
What vacancy rate should I use?
The vacancy rate depends on your local market and property type. A 5% vacancy rate is common for well-located properties in strong rental markets, while 8-10% may be more realistic for properties in areas with high competition or seasonal demand. Check local market data and your own historical occupancy to set an accurate rate.