Quick answer
Net operating income NOI = rent × 12 × (1 − vacancy) − operating expenses × 12, and cash flow = NOI − debt service. A $300,000 property with 25% down, 6.5% over 30 years, $2,400 rent, 5% vacancy has NOI of $18,960, debt service of $17,065.84, cash flow of $1,894.16 and a cap rate of 6.32%.
Enter price, down payment, mortgage terms, rent, vacancy and monthly operating costs. The calculator returns NOI, debt service, cash flow, cap rate and cash-on-cash return. Use this rental property calculator to check your own figures.
Related tools: Rental Yield Calculator: Gross and net rental yield on a property. Cap Rate Calculator: Capitalization rate of an income property. Cash on Cash Return Calculator: Annual pre-tax cash flow relative to the cash you invested.
How to use the Rental Property Calculator
- Enter purchase price ($) (above 0).
- Enter down payment (%) (between 0 and 99).
- Enter mortgage rate (%) (between 0 and 100).
- Enter mortgage term (years) (a whole number, between 1 and 50).
- Enter monthly rent ($) (above 0).
- Enter vacancy (%) (between 0 and 100).
- Enter monthly operating expenses ($) (0 or more).
- Press Calculate to see the result, and use Reset to start again.
| Input | What to enter | Allowed values |
|---|---|---|
| Purchase price | A number, in $ | > 0 |
| Down payment | A number, in % | ≥ 0, ≤ 99 |
| Mortgage rate | A number, in % | ≥ 0, ≤ 100 |
| Mortgage term | A whole number, in years | ≥ 1, ≤ 50 |
| Monthly rent | A number, in $ | > 0 |
| Vacancy | A number, in % | ≥ 0, ≤ 100 |
| Monthly operating expenses | A number, in $ | ≥ 0 |
Formula and method
Formula
NOI = rent × 12 × (1 − vacancy) − expenses × 12; cash flow = NOI − debt service
IEEE-754 double precision; shown to the decimals indicated.
Operating expenses should include taxes, insurance, maintenance and management.
Worked examples
These examples are verified: each one is an automated test case that the live calculator must reproduce exactly.
Example 1
Inputs: Purchase price = 300000; Down payment = 25; Mortgage rate = 6.5; Mortgage term = 30; Monthly rent = 2400; Vacancy = 5; Monthly operating expenses = 700.
| Result | Value |
|---|---|
| Annual cash flow | $1,894.16 |
| Net operating income | $18,960.00 |
| Annual debt service | $17,065.84 |
| Cap rate | 6.32% |
| Cash-on-cash return | 2.53% |
Example 2
Inputs: Purchase price = 180000; Down payment = 20; Mortgage rate = 7; Mortgage term = 30; Monthly rent = 1600; Vacancy = 8; Monthly operating expenses = 500.
| Result | Value |
|---|---|
| Annual cash flow | $167.57 |
| Net operating income | $11,664.00 |
| Annual debt service | $11,496.43 |
| Cap rate | 6.48% |
| Cash-on-cash return | 0.47% |
The first line is the headline result (annual cash flow). Below it the rental Property Calculator lists net operating income, annual debt service, cap rate and cash-on-cash return, which describe the same case from other angles. IEEE-754 double precision; shown to the decimals indicated.
Putting it together
Rent after vacancy is $2,400 × 12 × 0.95 = $27,360; subtracting operating expenses leaves NOI of $18,960. The loan of $225,000 costs $17,065.84 a year, leaving $1,894.16.
Reading the results
A cap rate of 6.32% measures the property's yield unlevered; the cash-on-cash return measures the return on the cash you invested. Taxes, appreciation and capital expenditure aren't included, so keep a reserve.
How the result changes with purchase price
Holding every other input at the first worked example, this table changes only purchase price. It shows how sensitive the answer is to that one value; each row was produced by running this calculator.
| Purchase price | Annual cash flow | Net operating income | Annual debt service |
|---|---|---|---|
| 150000 | $10,427.08 | $18,960.00 | $8,532.92 |
| 300000 | $1,894.16 | $18,960.00 | $17,065.84 |
| 600000 | -$15,171.67 | $18,960.00 | $34,131.67 |
| 1200000 | -$49,303.35 | $18,960.00 | $68,263.35 |
What happens with invalid input
These messages are produced by the calculator itself, so you know what to fix.
- Down payment: entering "0" shows "Enter a down payment above zero to measure cash-on-cash return." beside that field and no result.
- Purchase price: entering "0" shows "Purchase price must be greater than 0." beside that field and no result.
Choosing between the Rental Property Calculator and similar calculators
Each row shows what a related calculator on this site asks for and what it returns, so you can pick the one that matches your question.
| Calculator | You enter | It returns |
|---|---|---|
| [Rental Yield Calculator](/real-estate/rental-yield-calculator/) | monthly rent and property price | Gross yield |
| [Cap Rate Calculator](/real-estate/cap-rate-calculator/) | net operating income and property value | Cap rate |
| [Cash on Cash Return Calculator](/real-estate/cash-on-cash-return-calculator/) | annual pre-tax cash flow and total cash invested | Cash-on-cash return |
| [House Flipping Profit Calculator](/real-estate/house-flipping-profit-calculator/) | purchase price, renovation cost and holding costs | Profit |
| [Real Estate ROI Calculator](/real-estate/real-estate-roi-calculator/) | purchase price, sale price and net income during ownership | ROI |
Background: rental property metrics
Rental property metrics answer different questions. The cap rate is net operating income divided by the purchase price and ignores financing; cash flow is income minus operating expenses minus debt service; cash-on-cash return divides annual cash flow by the cash you actually invested. Rules of thumb such as the 1% rule (monthly rent at least 1% of the price) are quick screens, not decisions.
Check the assumptions behind any result: vacancy, management fees, repairs and taxes. Published benchmark ranges for a good cap rate or return vary between sources.
Assumptions and limitations
- Down payment must be above zero
Estimates only. Taxes, fees and lender or authority rules vary by place and date, so confirm figures with the relevant authority or professional.
If a required value is empty, not a number, or outside its allowed range, the form marks that field with a message and shows no result instead of a misleading number. The automated checks deliberately try invalid entries for down payment and purchase price to confirm this.
Frequently asked questions
What is vacancy?
Time a unit stands empty.
What costs are operating expenses?
Taxes, insurance, repairs and management.
Is positive cash flow enough?
Check returns against alternatives.
What does the Rental Property Calculator calculate?
Cash flow, cap rate and cash-on-cash return of a rental. It returns Annual cash flow, Net operating income, Annual debt service, Cap rate and Cash-on-cash return.
What formula does the Rental Property Calculator use?
NOI = rent × 12 × (1 − vacancy) − expenses × 12; cash flow = NOI − debt service. Operating expenses should include taxes, insurance, maintenance and management.
What do I need to enter in the rental Property Calculator?
You enter Purchase price ($), Down payment (%), Mortgage rate (%), Mortgage term (years), Monthly rent ($), Vacancy (%) and Monthly operating expenses ($).
How is the result rounded or limited?
IEEE-754 double precision; shown to the decimals indicated. Down payment must be above zero.
What is an example of a rental Property result?
With purchase price 300000, down payment 25, mortgage rate 6.5, mortgage term 30 and monthly rent 2400, the annual cash flow is $1,894.16.
Can I rely on this calculator for a decision?
Estimates only. Taxes, fees and lender or authority rules vary by place and date, so confirm figures with the relevant authority or professional. For this calculator in particular: Down payment must be above zero.
Related calculators
- Rental Yield Calculator — Gross and net rental yield on a property.
- Cap Rate Calculator — Capitalization rate of an income property.
- Cash on Cash Return Calculator — Annual pre-tax cash flow relative to the cash you invested.
- House Flipping Profit Calculator — Profit and return on cost of a renovate-and-sell project.
- Real Estate ROI Calculator — Total return on a property from sale gain and net income.
- Vacancy Rate Calculator — Share of rental units that are vacant, with optional lost rent.
Sources
- Common definition used on this page. No single authoritative standard defines it, so the exact formula is stated in the formula section above
Content last reviewed 2026-11-04. Formulas and worked examples are checked by automated tests against independently computed values.