Start with the rental money you expect to collect, then subtract the bills you expect to pay. This calculator shows cash flow before and after the replacement savings you choose. It also compares the annual cash left with the cash you invested.
What you enter
Enter expected room revenue, any cleaning income and the costs charged against that revenue. Add management, platform fees, cleaning expenses, utilities, maintenance, property taxes, insurance, HOA dues and the full mortgage payment. Enter a separate allowance for furniture and other future replacements.
Use either annual totals or a full set of monthly figures. A monthly view is better for seeing a slow season, while an annual view avoids treating a strong month as a normal month. Do not enter a fully collected revenue estimate and then subtract the same vacancy reduction again.
Cash invested includes the cash actually committed to buying and launching the rental. That can include the down payment, transaction costs, furnishing and initial operating cash. Choose one definition and keep it the same when comparing properties. This page does not calculate taxes on income or depreciation. Have a CPA review those separately.
Example
Assume $72,000 of annual collected rental revenue. Assume $24,000 in operating cash costs, $36,000 in mortgage payments and $6,000 set aside for future replacements. All figures are hypothetical.
Cash flow before replacement savings is $12,000 a year. After the $6,000 allocation, $6,000 remains, or an average of $500 a month. With $150,000 of cash invested under the definition above, the modeled cash on cash return after replacement savings is 4%.
That average does not promise a $500 deposit every month. Actual receipts, repairs and renewal bills arrive on their own schedule. Review the monthly view before deciding how much operating cash to keep.
What is my monthly cash flow?
It is collected revenue less the included operating costs and mortgage cash payments for that month. When you enter annual figures, the monthly figure is an average, not a forecast of a particular month.
The tool should label the selected basis clearly. An annual average can hide a monthly deficit.
What is my cash flow after reserves?
Here, it is cash flow less your chosen replacement savings allocation. That allocation is separate from any loan reserve requirement and from costs already paid.
Avoid subtracting a replacement allowance and the same planned purchase twice. See How to Underwrite a Rental Property Before an Offer for the wider budget review.
How do management and cleaning change it?
They reduce cash left to the extent they create costs not offset by included revenue. Enter the actual fee basis and cleaning charges rather than assuming a percentage applies to every receipt.
The tool can use a flat amount when a contract does not fit a simple percentage model. Do not assume a guest cleaning charge covers the full turnover cost.
What is my cash on cash return?
It is annual modeled cash flow divided by your defined cash invested, expressed as a percentage. This calculator reports both before and after replacement savings.
It excludes appreciation, principal equity gains and sale proceeds from that return. Those belong in a different investment calculation.
This calculator gives an estimate only. It is not a loan offer or approval.
Sources
- OCC Commercial Real Estate Lending Handbook. Income Generating Capacity of CRE, Debt Service Coverage Ratio and Value Analysis, printed pages 42 to 44. Checked October 16, 2026.
- CFPB Mortgage payment components. What goes into my total monthly mortgage payment; reviewed August 28, 2023. Checked October 16, 2026.
- Fannie Mae Mortgage Calculator. Disclaimer; How to use this calculator. Checked October 16, 2026.