Guide
Rental property cash flow calculator: CoC, DSCR, and monthly cash flow
Cash flow is what is left after operations and debt service, using the assumptions you enter. This page defines monthly cash flow, cash-on-cash return, and DSCR, and points to a free calculator whose math matches our published workbook sample.
Open the free cash flow calculator
The definitions we use
Annual cash flow = NOI − annual debt service
Monthly cash flow = annual cash flow ÷ 12
Cash-on-cash = annual cash flow ÷ total cash invested
DSCR = NOI ÷ annual debt service
Total cash invested is the down payment (purchase price minus the loan) plus closing costs plus rehab. The monthly loan payment is a standard amortizing payment — the same PMT function used in Excel and Google Sheets. If you type a loan of zero, the payment is zero and DSCR is left blank (you cannot divide by zero).
We also show cash flow after a CapEx reserve. The reserve is a percentage of effective gross income that you set. It is subtracted after NOI, not inside NOI, so cap rate and DSCR stay consistent with a common underwriting convention.
Worked sample (demonstration only)
On the sample deal (a $200,000 price, $150,000 loan at 6.5% for 30 years, $2,000 monthly rent, and the sample operating costs):
- Total cash invested: $64,000
- Monthly payment: $948.10
- NOI: $15,936
- Annual cash flow: $4,558.78
- Monthly cash flow: $379.90
- Cash-on-cash: 7.12%
- DSCR: 1.40
- After a 5% CapEx reserve: $3,418.78 annual, $284.90 monthly
These come from the same inputs as “Deal 1” in our SAMPLE workbook and are labeled sample layout only. Load them on the calculator with one click and compare. A test script ships with this site and must pass before we consider the tool ready.
An illustrative stress test, not a forecast
The calculator can re-run the deal with rent 10% lower, vacancy 5 percentage points higher, and the interest rate 2 points higher. On the sample, stressed cash flow is negative (about −$828 a year). That is an illustration of sensitivity. A negative result is not a recommendation to walk away; a positive result is not a recommendation to buy.
Cap rate sits next to cash flow, not above it
Cap rate uses NOI and price only — it does not see your loan. Cash-on-cash and monthly cash flow do. Looking at both is how many investors describe a deal; it is still not a complete analysis. Taxes on the owner, deferred maintenance you did not reserve for, and local rent rules can all change a real outcome. See the cap rate guide for that formula.
When you want to save more than one deal
This free page does not store scenarios. The Rental Property Cash Flow Analyzer ($29.99) is a spreadsheet with five deal columns, a BRRRR sheet, logs, and a dashboard for up to 15 properties. It opens in Excel and in free Google Sheets. It is not investment advice, not a tax return, and not a Schedule E.