Rental Property Cash Flow Calculator
Calculate monthly cash flow on a financed rental property: rent minus operating expenses and vacancy (as a share of rent) minus the fully amortized mortgage payment. Use it when comparing rental properties to find which deal produces the strongest returns.
Last updated: September 2026
Formula below · 2 sources (CFPB, Wikipedia) · Updated Sep 2026
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About this calculator
Monthly cash flow equals the rent you keep after operating costs, minus the mortgage payment on the financed portion of the property. Operating costs and vacancy are entered as a share of rent (35% if you leave the field blank; 30–45% is typical for property tax, insurance, repairs, management, capital reserves and vacancy). The mortgage payment uses the standard amortization formula: M = P × [r(1+r)ⁿ] / [(1+r)ⁿ − 1], where P is the loan amount (property price × (1 − down payment %)), r is the monthly interest rate (annual rate ÷ 12), and n is the total number of payments (loan term in years × 12). Cash Flow = Monthly Rent × (1 − Expense %) − M. A positive result means the property generates income above all costs each month. Enter 0 for the expense share only if you want the raw rent-minus-mortgage figure, which overstates real cash flow.
How to use
A property costs $250,000 with 20% down ($50,000), leaving a $200,000 loan at 7% interest over 30 years. Monthly rate r = 0.07/12 = 0.005833; n = 360. M = $200,000 × [0.005833 × (1.005833)³⁶⁰] / [(1.005833)³⁶⁰ − 1] = $200,000 × 0.006653 = $1,330.60. Monthly rent is $1,800 and operating costs plus vacancy are 35% of rent ($630), so the rent you keep is $1,170. Cash flow = $1,170 − $1,330.60 ≈ −$160.60/month, signaling the deal needs a higher rent or a lower purchase price.
Frequently asked questions
What is a good monthly cash flow for a rental property?
A common benchmark is $100–$200 per door per month in net cash flow after all expenses, including mortgage, taxes, insurance, vacancy, maintenance, and management. In high-cost markets, investors sometimes accept break-even cash flow and rely on appreciation and loan paydown for total return. The 1% rule—monthly rent should be at least 1% of the purchase price—is a quick filter many investors use to identify properties likely to cash flow positively. Always run full numbers rather than relying on rules of thumb alone.
How does the down payment percentage affect rental property cash flow?
A larger down payment reduces the loan principal, which lowers the monthly mortgage payment and improves cash flow. However, it also increases the cash invested, which can lower your cash-on-cash return (annual cash flow divided by cash invested). For example, putting 30% down instead of 20% on a $250,000 property reduces the loan by $25,000, saving roughly $166/month in payments but requiring $25,000 more upfront. Investors must balance cash flow improvement against the opportunity cost of deploying more capital.
Why is cash flow only part of the picture when analyzing a rental property?
Cash flow measures income after debt service but ignores three other return components: principal paydown (your tenant effectively pays down your loan each month), tax benefits (depreciation and expense deductions), and appreciation (property value growth over time). A property with modest cash flow can still deliver a strong total return if it appreciates well and offers significant tax shelter. Conversely, a high-cash-flow property in a stagnant market may underperform a low-cash-flow asset in a growing city when total return is measured over a 10-year hold.