What Is Rental Cash Flow?
Rental cash flow is the money a property puts in your pocket each month after you subtract every operating expense and your mortgage payment from the rent you actually collect. When income is higher than costs, the property is cash-flow positive; when costs win, it's cash-flow negative. It's the single clearest signal of whether a rental pays you to own it or costs you to hold it.
The calculator above turns that definition into a number in seconds. You enter your rent, vacancy allowance, operating expenses, and mortgage, and it returns your monthly cash flow and annual cash flow. These are the two figures that tell you, before you buy or renew, whether the deal works.
The rental cash flow formula
Effective rental income is your gross rent minus a vacancy allowance (the rent you lose while the unit sits empty between tenants). Multiply the monthly result by 12 to get your annual cash flow.
A worked example
Say you rent a single-family home for $2,000 a month and budget a 5% vacancy rate:
This property is cash-flow positive at $190 per month, which sits inside the range many landlords consider healthy. Change any input in the calculator (a higher interest rate, a bigger tax bill, a longer vacancy) and you'll instantly see how quickly a “good” deal can slip into the red.
How To Use This Rental Cash Flow Calculator?
Each field maps to a real cost of owning a rental. Enter your best estimate for every line. The more honest your inputs, the more reliable your result.
- Monthly rent: the rent you expect to collect each month. Base it on comparable listings in the neighborhood, not on hope.
- Vacancy rate (%): the share of the year the unit sits empty. Budgeting 5% to 10% is a common, conservative starting point. Adjust it for local demand and turnover.
- Property taxes ($/month): take your annual county tax bill and divide by 12.
- Insurance ($/month): your landlord or dwelling policy premium as a monthly figure. Get a real quote, since investment-property rates differ from owner-occupied.
- Maintenance & repairs ($/month): set aside a reserve. A common rule of thumb is 1% to 2% of property value per year, or roughly $100 to $150 a month for a typical single-family rental.
- Property management fee (%): if you use a manager, expect 8% to 12% of monthly rent. Self-managing? Enter 0, but remember your time still has value.
- HOA fees ($/month): condos and many planned communities charge dues that eat directly into cash flow.
- Monthly mortgage payment ($): your principal and interest (and, if escrowed, taxes and insurance). If it already includes taxes and insurance, don't double-count those above.
What Is a Good Monthly Cash Flow For a Rental?
There's no universal number, but experienced U.S. investors often target $100 to $300 in cash flow per unit, per month for long-term rentals. The reasoning is practical: a cushion of a few hundred dollars per door helps absorb a surprise repair, a slow month, or a rate increase without pushing the property into the red.
Two quick rules of thumb help you screen deals before you ever open a spreadsheet:
- The 1% rule: monthly rent should be at least 1% of the purchase price (a $200,000 home should rent for roughly $2,000 a month). It's a fast filter, not a guarantee.
- The 50% rule: assume operating expenses (excluding mortgage principal and interest) will run about 50% of gross rent. It's a sanity check for whether your expense estimates are realistic.
Treat these as filters, not verdicts. A property that clears both rules can still lose money after financing, and one that misses them can still be a smart buy in a strong appreciation market. Always finish with a full calculation like the one above.
How To Increase Your Rental Cash Flow?
If your result is thin or negative, cash flow moves on two levers: raising collected income and cutting avoidable costs.
- Cut vacancy and turnover. An empty unit is your single most expensive line item. Placing reliable, long-staying tenants is the fastest way to protect income, which is why screening applicants thoroughly with tenant background screening matters as much to your bottom line as the rent number.
- Qualify tenants on income up front. Rent you never collect isn't income. Checking that an applicant earns enough with a rent-to-income ratio calculator reduces the risk of missed payments later.
- Make on-time rent effortless. Late and partial payments quietly wreck monthly cash flow. Moving tenants onto automated online rent collection helps keep the money arriving on schedule.
- Trim recurring expenses. Reshop insurance annually, appeal an over-assessed tax bill, and get competitive bids on management and maintenance.
- Raise rent to market carefully. Below-market rent is common with long-term tenants. Small, well-communicated increases at renewal can restore cash flow without triggering turnover.
For a deeper walkthrough with more examples, see our full guide on rental property cash flow.
Cash flow vs. Cash-on-cash Return vs. Cap Rate
Cash flow tells you how much a property earns each month. It doesn't tell you how good that return is relative to the cash you invested, and that's a different question.
A property earning $190 a month is great value on a $15,000 down payment and mediocre on a $90,000 one. Same cash flow, very different return. When you're ready to compare deals on return rather than raw dollars, run the numbers through the Rental Property ROI Calculator, which adds cap rate, cash-on-cash return, and ROI.
Frequently Asked Questions
Q1. How do I calculate rental cash flow?
Subtract your operating expenses and mortgage payment from the rent you actually collect: Cash Flow = Effective Rental Income (gross rent minus vacancy) - Operating Expenses - Mortgage. A positive number is monthly profit; a negative number means the property costs you money to hold.
Q2. What is a good monthly cash flow for a rental property?
Many U.S. investors aim for $100 to $300 per unit, per month on long-term rentals. That cushion helps cover surprise repairs, a slow month, or a rate increase. The right target depends on your market, property type, and whether you're prioritizing cash flow or appreciation.
Q3. Is negative cash flow always bad?
Not always. In high-appreciation markets, some investors accept short-term negative cash flow as a planned phase, betting on rising rents and value. It's only sustainable if you can comfortably cover the monthly shortfall and have a clear timeline for turning positive.
Q4. Does this calculator include cash-on-cash return or cap rate?
No. This tool focuses on monthly and annual cash flow. For cash-on-cash return, cap rate, and overall ROI, use the Rental Property ROI Calculator, which factors in your purchase price and total cash invested.
Q5. How much should I budget for vacancy and maintenance?
A conservative starting point is 5% to 10% of annual rent for vacancy and 1% to 2% of the property's value per year for maintenance. Older properties and high-turnover markets warrant the higher end of both ranges. Adjust as you gather real operating history.
Q6. Should my mortgage figure include taxes and insurance?
Only if you don't enter them separately. If your monthly mortgage payment already escrows property taxes and insurance, leave those fields at zero to avoid double-counting. Otherwise, enter principal and interest in the mortgage field and taxes and insurance in their own lines.
Run Your Numbers Before You Commit
A rental only builds wealth when it cash flows, or when you've deliberately chosen to carry it for appreciation with eyes open. Use the calculator above to pressure-test every property before you buy, renew, or refinance, then protect the cash flow you've modeled by placing reliable tenants and collecting rent on time. Create a free LeaseRunner account to screen applicants, verify income, and automate rent collection in one place.
Disclaimer: The information provided in this post is intended for general informational and educational purposes only. It should not be construed as legal, accounting, or tax advice. For guidance specific to your situation, we recommend consulting with a qualified professional in the relevant field before taking any action based on the content provided.
