How it works
How this tool works.
Whether a rental is a good deal comes down to a few numbers most listings never show you: the cap rate, what it clears each month after the mortgage, and how hard your down payment is working. Run them before you make an offer, not after.
Enter the purchase price, rent, operating expenses, and your financing, and this calculator estimates all three at once. It’s arithmetic on the figures you provide — an illustration to compare deals, not a prediction of what any property will actually return.
Enter the purchase price, monthly rent, and annual operating expenses (excluding the mortgage — put taxes and insurance here).
Set your down-payment percentage, mortgage APR, and loan term; the tool computes the monthly principal & interest with a standard amortization formula.
It returns cap rate (NOI ÷ price), monthly cash flow (NOI ÷ 12 − mortgage P&I), and cash-on-cash (annual cash flow ÷ your down payment).
Every output is an estimate from your inputs — it excludes closing costs, appreciation, tax effects, and vacancy, so treat it as a comparison tool.
Make the result useful
Rental ROI interpretation
Purchase price anchors cap rate; use a supportable acquisition price.
NOI is annual income after operating expenses but before debt service and income taxes.
Financing inputs affect cash flow and cash-on-cash, not cap rate.
Cash invested should include down payment, closing, and immediate cash-funded work.
The assumptions that move this result
Price
Purchase price used for cap-rate comparison.
NOI
Annual operating income before debt service.
Debt service
Annual or monthly modeled loan cost.
Cash invested
Cash actually committed to the deal.
cap rate = NOI ÷ price; cash-on-cash = annual pre-tax cash flow ÷ cash invested
Use the output as a documented scenario result, not a guarantee.
Read the number in context
Worked scenario
Scenario: $24,000 NOI on $300,000 price is 8% cap rate.
Edge case
Edge case: omitting closing cash raises a cash-on-cash result without increasing actual return.
This does not forecast rent, appraisal, repairs, or investment performance.
Before you act
• Rebuild NOI from an itemized operating budget.
• Test vacancy and repair downside cases.
• Read cash flow and debt coverage beside return percentages.
Worked formula
cap rate = NOI ÷ price; cash-on-cash = annual pre-tax cash flow ÷ cash invested
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.