Rental cash flow calculator
Enter the price, loan terms, rent, and expenses. Get monthly cash flow, cash-on-cash return, and a 1% rule check instantly — no signup, no email.
Cash-on-cash divides annual cash flow by the down payment; closing costs are assumed at $0, so add yours for a real deal. General information, not financial advice.
How to calculate rental cash flow
Cash flow is the money left each month after every bill is paid: the vacancy allowance, operating expenses, and the mortgage. Cap rate stops before the loan; cash flow goes all the way through it, which makes it the number that actually lands in your bank account.
Take the defaults above: a $250,000 purchase with 20% down leaves a $200,000 loan, and at 7.0% over 30 years the payment is about $1,331 a month. Rent of $2,200 less a 5% vacancy allowance gives $2,090 of effective gross income; taxes, insurance, 8% management, and maintenance total about $667. That leaves about $92 a month, a 2.2% cash-on-cash return on the $50,000 down payment.
A thin result like that is what a 0.88% rent-to-price ratio buys at 7% rates. For the inputs behind the math, see cash-on-cash return, net operating income, the 1% rule, and the step-by-step guide to analyzing a rental.
What is a good cash-on-cash return on a rental?
Investors commonly cite 8–12% as a solid target, but the achievable number moves with interest rates and the market. At current financing costs, many clean deals in stable metros pencil in the 4–8% range, and buyers accept less for better neighborhoods and tenants. This is general information, not financial advice; what counts as good depends on your alternatives and goals.
Does cash flow include the mortgage payment?
Yes. Cash flow is what's left after the mortgage, which is exactly what separates it from cap rate: cap rate stops at net operating income, before any debt service. Two buyers with different loans get different cash flow on the same property but the same cap rate.
What expenses do people forget?
Capital expenditures and vacancy are the two big misses. A roof or HVAC replacement doesn't show up in the monthly bills until it lands all at once, so budget a capex reserve (many investors set aside 5–10% of rent) on top of routine maintenance. Skipping the vacancy allowance overstates income by a full month's rent for every month the unit sits empty.
Is the 1% rule still realistic?
In most coastal and high-appreciation metros, no; in parts of the Midwest and South it still shows up, mostly on older or smaller properties. It works as a fast screen: below about 0.8%, positive cash flow at 20% down and current rates is hard to reach without unusually low expenses.
Cash flow is one lens on a deal. CapScout runs the mortgage, expenses, comps, and a full ScoutSense underwrite on every listing.
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