Rental Cash Flow Calculator
This is the two-minute health check for a rental you own or one you’re sizing up. Enter what comes in and what goes out each month, and you’ll see the number that matters most: what’s actually left in your pocket. Positive means the home pays you. Negative means you’re paying it, and you should know exactly how much.
Every field updates the results instantly. No email required, and nothing you enter leaves this page.
Get it wrong by $100 and every metric on this page moves. We price homes across NC and SC every day, and a virtual rental evaluation with a custom cost quote is free.
The Six Numbers, Explained Like a Neighbor Would
Each result the calculator gives you, what it means, and the one worked example we’ll carry through: a home collecting $1,380 a month, spending $595 on operations, and paying an $800 mortgage.
Monthly Net Cash Flow: What’s Left in Your Pocket
Take everything the home brings in, subtract everything it costs, mortgage included. Our example home: $1,380 in, $1,395 out, so cash flow is negative $15 a month. That doesn’t sound scary, but it means the home isn’t paying for itself; you are. Plenty of owners chase appreciation while quietly feeding a property every month, and a stretch of negative cash flow is exactly what forces people to sell at the worst possible time. Know this number cold.
Annual Cash Flow: The Same Truth, Times Twelve
Negative $15 a month is $180 a year you’re contributing from your own funds. Small on one home. But three homes each losing a little becomes real strain, and it compounds with every surprise repair. On the other side of the ledger, a small yearly loss can still be worth carrying when tax deductions, loan paydown, and appreciation outweigh it. The point isn’t that negative is always bad; it’s that you should choose it on purpose, with the math in front of you.
Net Operating Income: The Number Professionals Watch
NOI is income minus operating costs, before the mortgage. Our example: $1,380 minus $595 is $785 a month, or $9,420 a year. Why leave out the mortgage? Because financing is a choice about you, not a fact about the home. Two investors can own identical houses, one paid in cash and one leveraged to the hilt, and NOI will read the same for both. That makes it the honest way to compare properties and the number that ultimately sets what a property is worth.
We build our whole management approach around NOI because it forces the right trade-offs. It rewards steady occupancy over trophy rents, and durable cost control over corner-cutting. A property with strong NOI performs well no matter what interest rates do next.
Total Income and Total Expenses: The Two Levers
Unlike a stock, a rental gives you direct control of both sides of the ledger. On the income side, rent is the headline, but pet fees, parking, and storage add up; our example’s $1,380 might be $1,250 base rent plus $130 in extras. On the expense side, roughly 60 to 70% is fixed (mortgage, taxes, insurance, HOA) and the rest is variable (maintenance, management, utilities). The fixed costs you negotiate once, at purchase and refinance. The variable costs you manage every month, and they’re where good habits quietly build wealth.
Expense Ratio: Your Efficiency Gauge
Divide total expenses by total income. Our example home runs 101%, which is the polite way of saying it spends more than it makes. Healthy single-family rentals run 35 to 50%; small multifamily 40 to 55%. If your ratio creeps above 60%, something structural is wrong: taxes, dues, or an aging home that needs a plan, not patches. And be suspicious of a ratio that looks too good; it usually means maintenance is being skipped, and skipped maintenance always comes back with interest.
Vacancy Is Setting Cash on Fire
Every empty day, the fixed costs keep running and no rent comes in. Our example home burns about $46 a day vacant: 30 days empty costs $1,380 in lost rent plus $595 in expenses that didn’t pause, $1,975 in total. Sixty days doubles it. Which reframes the pricing question entirely: a $100 rent reduction that prevents one month of vacancy saves $775 in the first month alone, and usually lands a stronger resident too. That’s why we test every rate decision against our Vacancy Cost Calculator before falling in love with a bigger number.
Competitive Pricing Fixes Problems You Haven’t Had Yet
When a home is priced fairly, applicants with options choose it on value. Those residents tend to have stable income and solid credit, they take care of the place, and they renew, which means fewer turnovers, fewer repair surprises, and better numbers on every line of this calculator. Overprice it and the strong applicants pass, the home sits, and you end up choosing from whoever’s left. Fair pricing isn’t generosity; it’s the highest-return decision in rental management, and it happens to treat residents well at the same time.
Putting It Together
Don’t optimize any one number. Price competitively to keep the home full, maintain it proactively so it earns market rent, collect the ancillary income it fairly supports, and control expenses without starving the property. Sometimes that means accepting slightly lower cash flow this year to protect NOI for the next five. We play the long game, and the long game is where rentals win.
Sizing up a purchase rather than a home you own? Run the full deal, financing and all, through our Investment Analysis & 5-Year Projection.
Our lease is written by the Bar Association and does a good job of protecting both residents and rental owners under the laws in our area.
