How to Calculate NOI — Step-by-Step Guide
Last Updated: 2026-03-27
NOI = Effective Gross Income − Operating Expenses. Start with total rental income, subtract vacancy losses to get Effective Gross Income, then deduct all operating expenses (taxes, insurance, maintenance, management). Do not include mortgage payments or depreciation.
Step-by-Step NOI Calculation
Follow this professional methodology used by institutional underwriters to calculate a reliable, defensible NOI figure.
1. Calculate Gross Income
Sum all income sources: base rent, parking fees, laundry, pet fees, storage, and any other ancillary revenue. Use actual collected rent (T12), not scheduled or pro-forma rents.
2. Apply Vacancy & Credit Loss
Deduct a realistic vacancy factor (typically 5–10% for stabilized properties). Also account for credit losses from tenants who don't pay. This gives you the Effective Gross Income (EGI).
3. Deduct Operating Expenses
Subtract all costs required to operate the property: property taxes, insurance, maintenance, management fees, utilities, and reserves. Do NOT include mortgage payments, depreciation, or capital expenditures.
Operating Expense Breakdown
Operating Expense Breakdown
Understanding each expense category is critical for accurate NOI calculation. Professional underwriters never accept a seller's expense figures at face value—they verify every line item against industry benchmarks and actual receipts. Fixed Expenses (predictable, contract-based): - Property Taxes: Typically 1–3% of assessed value. Critical: taxes often increase after a sale to reflect the new purchase price. - Insurance: Property, liability, and umbrella coverage. Rates vary by location and building age. Variable Expenses (fluctuate with occupancy and usage): - Maintenance & Repairs: Budget 5–10% of gross income. Older buildings skew higher. - Utilities: Owner-paid water, sewer, trash, and common area electric. Tenant-paid utilities should NOT appear here. - Management Fees: Typically 4–8% of collected rent for third-party management. Reserves (set aside for future capital needs): - Replacement Reserves: $250–$500 per unit/year for multifamily. Covers HVAC, roofing, and appliance replacement.
Real-World NOI Examples
See how NOI varies across property types. These 2026 benchmarks help you assess whether your property's income is competitive.
| Property Type | Gross Income | OpEx | NOI | Margin |
|---|---|---|---|---|
| 20-Unit Multifamily (Austin) | $360,000 | $126,000 | $234,000 | 65% |
| Class B Office (Phoenix) | $285,000 | $128,250 | $156,750 | 55% |
| NNN Retail (National Tenant) | $210,000 | $21,000 | $189,000 | 90% |
| Industrial Warehouse (Midwest) | $180,000 | $54,000 | $126,000 | 70% |
NOI vs. Cash Flow: Key Differences
Many investors confuse NOI with actual cash flow. Understanding the distinction is fundamental to proper deal analysis: - NOI measures the property's operational performance independent of financing. It tells you how well the building generates income. - Cash Flow = NOI − Debt Service (mortgage payments). This is what the owner actually takes home. - Before-Tax Cash Flow is what lenders use to calculate DSCR (Debt Service Coverage Ratio). Why does it matter? A property with strong NOI but excessive debt will have negative cash flow. Conversely, a free-and-clear property's NOI equals its cash flow. By isolating NOI, investors can compare properties regardless of how each is financed.
Expert NOI Tips
Avoid the most common mistakes that lead to inflated NOI projections and bad investment decisions.
The T12 Rule: Always use Trailing 12-Month actuals, never pro-forma projections. Sellers routinely inflate income and understate expenses in pro-forma statements to justify higher asking prices.
The Tax Reassessment Trap: Property taxes are almost always reassessed after a sale. If you're buying at $2M but the current tax basis is $800K, your future tax bill could triple. Always underwrite post-sale tax estimates.
Always Include Management: Even if you self-manage, deduct a 5–8% management fee. This ensures your NOI reflects the property's true economic performance, not your unpaid labor.