rental property cash flow calculator - Aaron Graves, PhDude Replica

Purchase & Financing

Purchase Price ($)

Down Payment (%)

Interest Rate (% APR)

Loan Term (Years)

Closing Costs ($ one-time)

Initial Rehab / Make-Ready ($ one-time)

Income

Monthly Rent ($)

Other Monthly Income ($)

Vacancy Rate (%)

Property Management (%)

Monthly Operating Expenses

Property Tax ($/month)

Insurance ($/month)

HOA ($/month)

Repairs & Maintenance ($/month)

Owner-Paid Utilities ($/month)

Other Expenses ($/month)

Why cash flow matters for rental properties

A rental property can look attractive on paper but still underperform in real life. Cash flow is the key metric that tells you whether the property can pay its bills, service debt, and put money in your pocket every month.

This calculator helps you estimate monthly and annual cash flow based on financing, rent, vacancy, and operating costs. It also shows common performance metrics like cap rate, cash-on-cash return, and DSCR.

How to use this rental property cash flow calculator

1) Enter purchase and loan details

Start with purchase price, down payment percentage, interest rate, and loan term. These values determine your loan amount and monthly principal & interest payment.

2) Estimate realistic income

Add monthly rent and any extra income (parking, laundry, pet fees, storage). Then apply a vacancy rate. Even strong markets have turnover, so underwriting with vacancy is essential.

3) Include all expenses

Many investors underestimate costs. Add property tax, insurance, HOA, repairs, utilities, and other recurring expenses. If you use management, the calculator applies a percent-based management cost to effective income.

4) Review the outputs

Monthly Cash Flow: money left after all monthly expenses including mortgage.
Annual Cash Flow: monthly cash flow multiplied by 12.
Cap Rate: annual NOI divided by purchase price.
Cash-on-Cash Return: annual cash flow divided by total cash invested.
DSCR: NOI divided by mortgage payment (higher is generally safer).

Pro tip: Run multiple scenarios (optimistic, expected, conservative). A deal that only works in a best-case scenario is usually too risky.

What is a “good” cash flow number?

There is no universal number, because taxes, financing terms, property class, and market conditions vary. Still, many investors look for:

Positive monthly cash flow after vacancy and reserves
A DSCR above 1.20 for financed deals
Cap rate and cash-on-cash return that beat alternatives in your market

The right target depends on your strategy. A value-add investor may accept lower initial cash flow in exchange for renovation upside. A conservative investor may demand strong in-place cash flow from day one.

Common mistakes when analyzing rental cash flow

Ignoring vacancy and turnover

Assuming 100% occupancy all year overstates performance. Budget for vacancy, cleaning, leasing, and make-ready periods.

Underestimating repairs

Every property needs maintenance. Older homes especially require a realistic monthly reserve for repairs and future capital expenditures.

Forgetting one-time cash requirements

Closing costs and initial rehab are part of your invested cash. Excluding them inflates cash-on-cash return.

Using market rent without validation

Verify rent assumptions with comparable listings, lease comps, and local property managers. Small rent errors can materially change returns.

Quick glossary

NOI (Net Operating Income): Effective income minus operating expenses (before debt).
Cap Rate: NOI / Purchase Price. A rough unlevered return measure.
Cash-on-Cash Return: Annual pre-tax cash flow / Cash invested.
DSCR: NOI / Debt service. Used by lenders to evaluate loan safety.

Final thoughts

A good rental property is built on disciplined underwriting. Use this calculator to quickly test deals, compare financing options, and understand how small assumption changes impact your cash flow. Then pair your numbers with local market research and a prudent risk buffer before making an offer.