Calculate Rental Property Cash Flow
See the full monthly waterfall — rent, vacancy, every expense, the mortgage, and reserves — plus the break-even rent this property needs. The honest version of "rent minus the mortgage."
What's left after every expense, the mortgage, and a reserve for big repairs.
Monthly cash-flow waterfall
Estimates for education only. Your real cash flow depends on the vacancy, maintenance, and CapEx assumptions above — the most common way beginners overstate it is by setting those too low.
Rent minus the mortgage isn't cash flow
The fastest way to lose money on a rental is to assume cash flow is just rent minus the loan payment. Real cash flow survives a vacancy allowance, property management, ongoing maintenance, and a reserve for the roof and furnace you'll eventually replace. This calculator subtracts each of those in turn so the final number is one you can actually rely on.
Watch the break-even rent: if market rent sits well above it, you have room for a bad month; if it's close, the deal is fragile. When you're ready for the full picture — returns, financing coverage, and a verdict — run the complete analysis.
What counts as good cash flow?
A widely-cited target is $100–$200 per unit per month after every expense and reserve — so a duplex might aim for $200–$400 in total. It's a useful floor because it leaves a cushion: enough that one surprise doesn't push the property into the red.
But the dollar figure alone can mislead. $150 a month on a property you put $15,000 into is a far better result than $150 on one that took $80,000. That's why serious investors pair the monthly number with cash-on-cash return — the percentage keeps the cash flow honest relative to what you invested. In pricey markets where cash flow is thin, some investors accept lower monthly income in exchange for stronger appreciation; just make that trade knowingly, not by accident.
Frequently asked questions
What is a good monthly cash flow for a rental property?
A common rule of thumb is $100–$200 per unit per month after all expenses and reserves, but the right target depends on your market, price point, and goals. What matters more than a single number is that the cash flow is positive after honest allowances for vacancy, maintenance, and capital expenditures — not just rent minus the mortgage.
How is rental cash flow calculated?
Start with gross rent, subtract a vacancy allowance to get effective income, subtract operating expenses (taxes, insurance, management, maintenance, HOA) to get net operating income, then subtract the mortgage payment and a capital-expenditure reserve. What remains is your cash flow. This calculator shows every step of that waterfall.
Why include vacancy, maintenance, and CapEx reserves?
Because they're real, recurring costs — units sit empty between tenants, things break, and roofs and HVAC eventually need replacing. Leaving them out is the single most common way new investors overstate cash flow and buy a property that actually loses money. Setting them to zero here will show you exactly how much they matter.
What is break-even rent?
Break-even rent is the monthly rent at which your cash flow is exactly zero — every dollar of rent covers a dollar of cost, with nothing left over. If your expected market rent is comfortably above break-even, you have a margin of safety; if it's close, small changes in vacancy or expenses can tip you negative.
How can I increase a rental's cash flow?
The biggest levers are price and financing — paying less or putting more down lowers the mortgage, the largest cash outflow. After that: raising rent to market, reducing vacancy with good tenants and quick turnovers, self-managing if you're able, appealing an inflated property-tax assessment, adding income like parking or laundry, and shopping insurance. Small improvements to several lines add up quickly.
What's the difference between cash flow and cash-on-cash return?
Cash flow is a dollar amount — what lands in your pocket each month or year. Cash-on-cash return expresses that annual cash flow as a percentage of the cash you invested, so you can compare it against other investments. A property can have modest cash flow in dollars but a strong cash-on-cash return if you invested very little, and vice versa.
Does positive cash flow mean it's a good investment?
It's necessary but not sufficient. Positive cash flow keeps the property self-sustaining, but the full picture also includes your return on invested cash, loan coverage, and appreciation. Run the complete analysis for a buy/pass verdict rather than relying on cash flow alone.