Rental cash flow calculator
How much is left each month after every bill is paid.
Designed for residential rental properties — single-family homes, condos, and small multifamily.
Monthly cash flow
$0.00
Annual cash flow
$0.00
Cash flow = Rent − vacancy − expenses − mortgage
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Cash flow is the money left in your pocket each month after the property pays every bill, including the mortgage.
Negative cash flow means you pay to own the property. Some investors accept this for appreciation, but it's the riskiest foundation.
How to calculate monthly rental cash flow
Start with monthly rent and subtract a vacancy allowance — even a great tenant eventually moves out, and 5% (about three weeks a year) is a prudent floor. Then subtract maintenance (5–8% of rent is typical for a sound property), property taxes, insurance, HOA dues, and management if you won't self-manage. Finally, subtract the full mortgage payment, principal and interest.
What's left is your monthly cash flow. On a $2,000 rental with a $1,247 mortgage, $425 of taxes and insurance, and standard vacancy and maintenance allowances, you're left with roughly $68 a month — positive, but thin. Thin margins are why the other numbers in a full rental property analysis matter: one vacancy spike or repair can erase a year of $68 months.
How much cash flow is enough?
A common rule of thumb is $100–$300 per door per month after all expenses and reserves. But the better test is resilience: would the property still break even if rent came in 10% lower, or if vacancy doubled? A deal that only works in the best case isn't cash flow — it's hope.
Also weigh cash flow against cash invested. $200 a month on $25,000 invested is a strong 9.6% cash-on-cash return; the same $200 on $150,000 invested is a weak 1.6%. Cash flow is the absolute number; cash-on-cash return puts it in context.
The expenses investors forget
Most negative-cash-flow surprises come from expenses that weren't in the original math: vacancy between tenants, turnover costs (paint, cleaning, re-keying), capital expenditures like roofs and water heaters, and management leasing fees. Budget 5% of rent for vacancy, 5–8% for ongoing maintenance, and set aside another 5% for big-ticket capital items on older homes.
If you self-manage, still run the numbers with 8–10% management included. Your time has a cost, and if you ever hire it out, the deal should survive the fee.
Cash flow vs appreciation markets
In high-cost coastal markets, many rentals cash-flow near zero and investors bet on appreciation. In the Midwest and South, $200–$400 monthly cash flow per door is still achievable. Neither is wrong, but they're different games: appreciation bets need deep reserves to survive negative months, while cash-flow deals build income from day one.
Whichever market you're in, run the stress tests before you buy. Our Full Financial Analysis shows your cash flow under five downside scenarios, plus your break-even rent — the minimum rent that keeps the deal afloat.
Frequently asked questions
What is good cash flow on a rental?
A common rule of thumb is $100–$300 per door per month after all expenses and reserves.
Should I budget for vacancy if the unit is rented?
Yes. Tenants move out. 5–8% is a sensible vacancy allowance for most markets.
Is negative cash flow ever acceptable?
Only with a clear reason — a value-add renovation, a below-market lease about to reset, or a strong appreciation bet — and enough reserves to fund the shortfall. For most investors, negative cash flow is a weak foundation.
Does cash flow include principal paydown?
No. Cash flow subtracts the whole mortgage payment. Principal paydown is a separate return that builds equity but doesn't spend like cash.