Rental Property Cash Flow Calculator

This calculator builds a rental property's monthly income statement from the ground up. It starts with gross rent plus any other income (parking, laundry, storage), then subtracts a vacancy allowance to get effective gross income — the money you can actually count on collecting. From there, property tax and insurance (entered as flat dollar amounts) are added to management, maintenance, and capital-expenditure reserves, each expressed as a percentage of effective gross income, to build total operating expenses. Subtracting those from effective gross income gives net operating income (NOI) — the property's earning power before financing.

Finally, the mortgage payment (principal and interest only, since taxes and insurance are already counted separately above) is subtracted to arrive at true monthly and annual cash flow. Two headline metrics follow directly from these numbers: cash-on-cash return (annual cash flow divided by the actual cash you put in — down payment, closing costs, rehab) measures the yield on your invested dollars, while cap rate (annual NOI divided by property value) measures the property's return independent of financing, letting you compare it against an all-cash purchase or another deal. The calculator also flags the classic 1% rule (is monthly rent at least 1% of purchase price?) as a quick screening heuristic, and reports an operating expense ratio so you can sanity-check your expense percentages against the common rule of thumb that operating costs should run near 50% of rental income. Because management, maintenance, and CapEx are all percentages of effective gross income rather than fixed dollar reserves, a property with lower rent will show proportionally lower expense line items even if actual repair costs don't scale down — treat those percentages as planning assumptions to be tuned to your market, not fixed truths.