How to read this result
In the default example, operating expense ratio is 30.00%. Results describe this input scenario; they are not a recommendation.
Change one assumption at a time to see how it affects the scenario. Compare periods and cost definitions consistently. Negative results show a modeled shortfall; an unavailable ratio needs a valid denominator.
Formula and methodology
Divide annual operating expenses by effective gross income, then express the ratio as a percentage. The dollar-per-dollar output shows the same relationship without multiplying by 100.
Enter percentages as whole numbers: 5 means 5%. When used as a factor, the calculation divides a percentage by 100. Percentage outputs multiply the final ratio by 100. Calculations retain precision internally; displayed amounts and rates are rounded to two decimals.
Variables and input definitions
- Annual operating expenses (USD/year)
- Recurring property operating expenses. Minimum: 0.
- Effective gross income (USD/year)
- Income after vacancy/credit loss. Minimum: 0.
Worked example
This example uses the exact prefilled inputs above. Reset defaults to restore this scenario after making changes.
| Item | Default scenario |
|---|---|
| Annual operating expenses | $18,000.00 |
| Effective gross income | $60,000.00 |
| Item | Default scenario |
|---|---|
| Operating expense ratio | 30.00% |
| Expense dollars per $1 of EGI | $0.30 |
Assumptions and limitations
Expense classifications vary by property type. Keep debt service, depreciation and income taxes outside operating expenses.
Results describe this input scenario; they are not a recommendation.
The tool uses values you supply. It does not retrieve market prices, verify leases or inspect a property. Results exclude items outside the listed inputs. Review local requirements and the relevant contract when a payment, fee or allocation depends on them.
Common mistakes
Using potential rent instead of effective income changes the denominator. Debt payments and depreciation do not belong in the ordinary operating expense input.
Sources and method references
These references provide context for the method and terminology. They do not endorse this tool or validate your property assumptions.
- IRS — Publication 527 (2025), Residential Rental PropertyRental income and expense concepts; operating/rental expense context.
- Office of the Comptroller of the Currency — Comptroller's Handbook — Commercial Real Estate LendingNOI, direct capitalization, cap-rate valuation and DCF concepts for commercial real estate.
Frequently asked questions
What does an OER of 30% mean?
The entered expenses consume 30 cents of each dollar of effective gross income. The remaining 70 cents are before financing and any costs excluded from the model.
Can operating expense ratio exceed 100%?
Yes. Expenses can exceed income. The ratio then exceeds 100%, indicating negative NOI under those operating assumptions.