Cash Flow Tool
Rental cash flow calculator that counts the expenses beginners miss.
Calculate true monthly and annual cash flow on any rental — with vacancy, management, maintenance, and reserves included — plus an AI verdict on whether the deal actually cash flows.
- Monthly and annual cash flow with realistic vacancy and reserves
- Cash-on-cash return so you compare deals fairly
- Free AI verdict and lender-ready PDF included
Honest expenses beat optimistic rent
Most cash flow mistakes come from skipping reserves or trusting a seller’s pro-forma rent. Model conservatively and your number holds up under real ownership.
Stress-test before you commit
Re-run the deal at a higher interest rate and vacancy. If it still cash flows, you have a margin of safety; if not, you negotiate or walk before earnest money is at risk.
What a rental cash flow tool actually measures
Cash flow is the money left after every expense and the mortgage are paid. A real cash flow tool does not stop at rent minus mortgage — it subtracts the costs beginners forget: vacancy, property management, maintenance, capital expenditure reserves, taxes, insurance, and HOA. ToInvested's free rental cash flow calculator models all of them and adds an AI verdict on whether the deal truly cash flows after realistic assumptions.
The cash flow formula
Cash flow = effective gross income − operating expenses − debt service − capital reserves. Effective gross income is your rent plus other income minus a vacancy allowance. Operating expenses are the running costs of the property. Debt service is your mortgage principal and interest. Reserves protect you from the roof and HVAC that eventually come due. Skip any line and your "cash flow" is fiction.
Cash flow vs cash-on-cash return
Cash flow is a dollar figure; cash-on-cash return turns it into a percentage by dividing annual pre-tax cash flow by the cash you invested. Two deals can both cash flow $300/month, but the one needing half the down payment earns a far better cash-on-cash return. The tool reports both so you compare deals fairly.
Why deals that look positive go negative
The most common reason a "cash-flowing" rental loses money: optimistic rent and missing reserves. Use conservative rent from real comps, a realistic vacancy rate, and honest maintenance and capex reserves. Then stress-test the interest rate — re-run at a point or two higher to see if the deal survives a rate move before you commit.
Run cash flow on a real deal
Enter price, rent, and expenses in the AI property deal analyzer and it returns monthly and annual cash flow, NOI, cap rate, DSCR, and cash-on-cash in one pass, with a BUY / PASS / CONDITIONAL verdict. Learn the full method in the real estate deal analysis guide, or see how lenders read the same numbers via DSCR and NOI.