How it works
How this tool works.
Operating expense ratio tells you how efficiently a property runs. It’s the share of gross operating income consumed by operating costs — taxes, insurance, management, repairs, and vacancy — before any mortgage. A lower ratio means more of each rent dollar survives to become net operating income.
Enter annual operating expenses and gross operating income, and this calculator estimates the ratio along with the NOI behind it. It’s arithmetic on your numbers, useful for comparing properties measured the same way.
Enter annual operating expenses — everything but the mortgage.
Enter gross operating income: annual rent plus other income, after a vacancy allowance.
The tool divides expenses by income to estimate the operating expense ratio.
Compare the ratio across similar properties, or track it over time on one you own.
Make the result useful
Operating-expense-ratio analysis
Operating expenses are recurring property costs before financing.
Effective gross income is income after vacancy/concessions on a stated basis.
Mortgage debt and capital projects should not be mixed into a recurring OER.
Compare the same period and accounting basis across properties.
The assumptions that move this result
Operating expenses
Recurring non-financing property costs.
Effective income
Income after modeled leakage.
Period
Matching annual or monthly period.
Expense basis
Consistent treatment of management and utilities.
operating expense ratio = operating expenses ÷ effective gross income
Use the output as a documented scenario result, not a guarantee.
Read the number in context
Worked scenario
Scenario: $18,000 expenses ÷ $45,000 effective income = 40%.
Edge case
Edge case: one large nonrecurring repair can distort a monthly ratio.
Does not measure debt service, capital needs, or property value.
Before you act
• Use effective—not scheduled—income.
• Separate capital projects.
• Compare itemized expense history.
Worked formula
operating expense ratio = operating expenses ÷ effective gross income
Is this a forecast?
No. It calculates the assumptions you enter.
Can it replace professional review?
No. Use current records and qualified advice.
What should I save?
Keep the assumptions and source records used for the decision.