Rental property
One Percent Rule Calculator
Test a chosen rent-to-cost target alongside vacancy, operating costs and debt service.
Calculate your result
What this calculator estimates
Compare monthly rent with acquisition cost. It combines the inputs below to produce Monthly rent as a percentage. Every assumption remains editable so the estimate can reflect the property, financing and location being evaluated.
Worked example
Using the displayed sample assumptions, the calculator produces 0.93%. This is an illustration, not a market quote. Change one input at a time to understand what drives the result.
Inputs and assumptions
- Purchase price — sample input: 350000 currency units
- Initial repairs — optional — sample input: 25000 currency units
- Closing costs — optional — sample input: 0 currency units
- Monthly scheduled rent — sample input: 3500 currency units
- Other monthly income — optional — sample input: 0 currency units
- Vacancy allowance — sample input: 5 %
- Monthly operating costs — sample input: 900 currency units
- Monthly debt service — sample input: 1600 currency units
- Target monthly rent-to-cost percentage — sample input: 1 %
How to interpret the result
Review cash flow together with reserves, vacancy and financing risk. Compare a conservative case with an expected case and keep a record of the assumptions used.
Common mistake to avoid
Do not treat gross rent as net operating income. Local definitions, taxes, lending practices and measurement requirements can materially change the result.
Calculation details
Monthly rent-to-cost = scheduled monthly income ÷ total acquisition cost. This screening ratio alone does not measure investment profitability.
Results included
- Monthly rent as percentage of acquisition cost
- Total acquisition cost
- Rent at your target percentage
- Rent difference from target
- Monthly vacancy allowance
- Monthly effective income
- Monthly NOI
- Monthly cash flow
- Annual cash flow
- Maximum total cost at target
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Reviewed 2026-09-08.