Real Estate & Investing
Rental Cash Flow Calculator
Combine financing, rent, and reserve assumptions on a single rental to see monthly cash flow alongside cap rate and cash-on-cash return.
Calculation inputs
Enter the purchase terms, rent, and recurring costs.
Results
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Complete the fields and select Calculate to show results here.
About this calculator
This calculator turns a rental property's price, financing, rent, and recurring costs into a monthly cash flow figure, plus cap rate and cash-on-cash return. Buyers, landlords, and analysts use it to test whether a specific deal actually produces spendable cash each month.
How the calculation works
- Loan amount = purchase price × (1 − down payment %)
- Monthly mortgage is a standard amortized payment on the loan amount, rate, and term
- Total monthly expenses = mortgage + taxes/12 + insurance/12 + HOA + maintenance % + vacancy % + management %
- Monthly cash flow = rent − total monthly expenses
- Cap rate = (annual rent − annual operating expenses excluding mortgage) ÷ price × 100
- Cash-on-cash = annual cash flow ÷ cash invested × 100
Notes and assumptions
Reserve percentages smooth out irregular costs; they are not monthly bills.
Add closing costs and any initial rehab to invested capital for a stricter cash-on-cash figure.
How it works in plain English
You start with the purchase price, down payment percentage, interest rate, and loan term, which together produce an amortized monthly mortgage payment covering principal and interest. Property taxes and insurance are entered as annual figures and divided by twelve to get a monthly cost, and HOA dues are added directly since they are already monthly.
Maintenance, vacancy, and property management are each entered as a percentage of rent rather than a fixed dollar amount, because those costs scale with rent level and occupancy rather than staying flat. Adding the mortgage payment to all of these operating costs gives total monthly expenses, and subtracting that from rent gives monthly cash flow.
Two other figures round out the picture. Cap rate divides annual income after operating expenses, but before the mortgage, by the purchase price, so it measures the property's own performance independent of financing. Cash-on-cash return instead divides annual cash flow by the actual cash invested (the down payment), showing the return on the money you put in rather than on the property's full value.
The formula
- Monthly cash flow = rent - (mortgage + taxes/12 + insurance/12 + HOA + maintenance% + vacancy% + management%)
- Cap rate = (annual rent - annual operating expenses excluding mortgage) / price x 100
- Cash-on-cash return = annual cash flow / down payment x 100
Worked example
A $285,000 rental is bought with 20% down ($57,000) at 6.75% over 30 years, giving a monthly mortgage near $1,479. Rent is $2,350, taxes $300/month, insurance $150/month, and reserves of 5% maintenance, 5% vacancy, plus 0% management add about $235 more. Total monthly expenses land near $2,164, leaving roughly $186 in monthly cash flow.
Annualized, that is about $2,232 in cash flow against $57,000 invested, a cash-on-cash return near 3.9%. The cap rate, which excludes the mortgage entirely, comes out higher because it measures the property's income against its full price rather than just the down payment.
Frequently asked questions
Why does cap rate ignore the mortgage but cash-on-cash return doesn't?
Cap rate is meant to describe how a property performs on its own, independent of how any specific buyer chooses to finance it, so it leaves the loan out entirely. Cash-on-cash return is meant to show your personal return on the cash you actually put down, so it must include the mortgage payment as an expense.
What counts as cash invested?
This calculator uses the down payment as cash invested. In practice you may also want to include closing costs, initial repairs, and any reserves set aside at purchase, since all of that cash is tied up in the deal before it produces any return.
Are the maintenance and vacancy percentages accurate for every property?
They are planning defaults, not guarantees. Older properties or ones with deferred maintenance often need a higher reserve, and areas with tighter rental demand may see lower vacancy. Adjust the percentages to match the property's age, condition, and local rental market.
Why is my cash flow negative even though the property seems reasonably priced?
Negative cash flow usually comes from a small down payment, a high interest rate, or rent that is low relative to the price. Increasing the down payment, shopping for a better rate, or finding a property with a higher rent-to-price ratio are the main levers to fix it.
Does this calculator account for income taxes or depreciation?
No. It works entirely in pre-tax, operating cash flow terms. Depreciation, mortgage interest deductions, and other tax effects vary by owner and situation, so they are left out and should be reviewed separately with a tax professional.
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