This rental property calculator estimates monthly cash flow after financing, operating expenses, and vacancy. Enter purchase price, down payment, loan rate and term, monthly rent, expenses, and a vacancy percent. The tool returns an approximate monthly cash flow figure for planning.
Investors use a rental property calculator before chasing a listing, comparing two addresses, or stress testing rent drops. It is a screening tool, not a full underwriting package.
What the calculator includes
The mortgage payment uses a standard amortizing payment on the loan amount (price minus down payment). Effective rent equals rent times one minus vacancy percent. Cash flow equals effective rent minus expenses minus the loan payment.
Worked example with default style inputs
Purchase price $300,000, down payment $60,000, loan rate 6.5 percent for 30 years, rent $2,400, expenses $500, vacancy 5 percent.
Loan amount is $240,000. The monthly payment is about $1,516.96. Effective rent is 2,400 × 0.95 = $2,280. Cash flow is 2,280 − 500 − 1,516.96 ≈ $263.04 per month.
| Item | Amount |
|---|---|
| Effective rent | $2,280 |
| Operating expenses | $500 |
| Loan payment | ~$1,516.96 |
| Monthly cash flow | ~$263 |
How to use the fields
- Price and down payment set the loan size.
- Rate and years drive the payment.
- Rent is expected monthly rent when occupied.
- Expenses should include insurance, taxes if paid monthly, HOA, management, maintenance reserves, and utilities you cover.
- Vacancy is a percent of rent you expect to lose to empty months or concessions.
Cash flow, NOI, and returns
This page focuses on levered monthly cash flow. Net operating income usually ignores the mortgage and focuses on income minus operating costs. Cash on cash return divides annual cash flow by cash invested.
For return focused screens, also try the ROI calculator after you settle on annual figures.
Vacancy and expense sensitivity
Raise vacancy and expenses to see when cash flow turns negative. A deal that only works at zero vacancy and tiny maintenance is fragile. Keep a maintenance reserve in expenses even if the seller pro forma omits it.
Financing notes
Payment math assumes a fixed rate amortizing loan. Use the mortgage calculator if you need a payment check in isolation.
Costs beyond the form
Closing costs, CapEx for roofs and HVAC, turnover painting, and property management fees change real results. Put recurring items into expenses. Treat large one time CapEx outside this monthly cash flow view.
Common mistakes
- Using optimistic rent without a vacancy line
- Forgetting taxes and insurance in expenses
- Comparing cash flow without matching down payment cash
- Ignoring turnover months after a tenant leaves
Limitations
The calculator does not estimate appreciation, tax depreciation shelters, or refinance proceeds. Local landlord rules and insurance availability still need human review.
Reserves and CapEx
Roofs, HVAC, and flooring are not monthly line items until you reserve for them. Add a monthly CapEx reserve into expenses so cash flow is not fake rich.
Management fees
Full service management often charges a percent of rent. Include it in expenses when you will not self manage.
Stress tests
Raise vacancy, raise rate, and lower rent in separate runs. A deal that only works in the best case is fragile.
Practical planning tips
Write down the inputs you used so you can repeat the estimate later. Small changes in rate, depth, hours, or price can move the result more than people expect.
When you compare two options, change one variable at a time. That keeps the comparison honest and easy to explain to a partner, client, or lender.
Units and rounding
Keep units consistent across every field. Mixing inches with feet, litres with gallons, or monthly figures with annual figures is the most common source of wrong answers.
Round only at the end for ordering or payments. Early rounding in each step can stack into a surprising gap versus the live calculator.
What this estimate does not include
Taxes, delivery fees, labor, penalties, and one time service charges are often outside the core formula. Add those on paper when you build a real budget.
Local rules, code requirements, and lender overlays can still change the final decision even when the math is correct.
How to double check the result
Recalculate once with a pencil using the same formula shown on this page. If your manual result is close to the tool, your inputs are probably consistent.
If the two answers diverge, check the field labels again before you trust either number for spending or filing.
When to get a second opinion
Large purchases, structural work, medical or legal questions, and loan contracts deserve a qualified human review. Use this page to prepare better questions, not to replace that review.
Save a screenshot or note of the inputs and result date. That record helps when you talk with a contractor, accountant, or lender later.