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Rental Property Calculator: Cash Flow, NOI, Cap Rate and Cash-on-Cash

A rental property calculator combines rent, vacancy, operating expenses, financing, and cash invested to estimate monthly cash flow and common property return metrics. It is a screening tool, not a valuation, tax, or investment recommendation.

Updated 2026-07-09Reviewed by US Finance Hub Editorial TeamCalculations run in your browser

Quick answer

Positive cash flow means projected rent exceeds operating costs and debt service under the entered assumptions. Cap rate excludes financing, while cash-on-cash return includes debt service and compares cash flow with cash invested.

At a glance

What it calculates
Estimate rental cash flow, net operating income, cap rate, and cash-on-cash return.
Who it is for
US buy-and-hold investors screening single-family and small multifamily deals before deeper due diligence.
Coverage
United States (federal rules; state and local rules vary)
Data and assumptions
Stabilised rent with a vacancy allowance, operating expenses you enter, and a fixed-rate amortising mortgage; no depreciation, income tax or appreciation.
Cost
Free, no signup, calculations run in your browser
Last reviewed
2026-07-09

Calculator

Enter your numbers

Agreed property price.
Cash down payment.
Cash costs not included in price.
Expected scheduled rent.
Expected rent not collected.
Taxes, insurance, repairs, management, utilities, and other operating costs.
Annual fixed rate.
Financing term.

How to use this calculator

  1. Enter price, down payment, and initial cash costs.
  2. Enter expected rent and vacancy.
  3. Add recurring operating expenses.
  4. Enter financing assumptions.
  5. Review cash flow and stress-test lower rent or higher repairs.

Explanation

What it is

A rental property calculator combines rent, vacancy, operating expenses, financing, and cash invested to estimate monthly cash flow and common property return metrics. It is a screening tool, not a valuation, tax, or investment recommendation.

How it works

The calculator reduces scheduled rent by vacancy, subtracts operating expenses to estimate NOI, then subtracts mortgage payments for cash flow. Cap rate divides annual NOI by price; cash-on-cash divides annual cash flow by initial cash invested.

When to use it

Use it to screen a listing before making an offer, and again with real quotes once you are under contract.

Limitations

  • Depreciation, income tax and 1031 treatment are outside the calculation.
  • Appreciation, rent growth and refinancing are not projected.
  • Insurance, property tax and regulation vary sharply by state and city.

Key terms

Net operating income
Property income after vacancy and operating expenses, before debt service and income taxes.
Cap rate
Annual NOI divided by property value or price.
Cash-on-cash return
Annual pre-tax cash flow divided by initial cash invested.
Vacancy allowance
Expected lost rent from vacancy or nonpayment.

Formula

The calculator reduces scheduled rent by vacancy, subtracts operating expenses to estimate NOI, then subtracts mortgage payments for cash flow. Cap rate divides annual NOI by price; cash-on-cash divides annual cash flow by initial cash invested.

NOI = effective rent − operating expenses; cash flow = NOI − debt service

Worked example

A $350,000 rental earning $3,000 monthly with 5% vacancy and $900 monthly operating costs can have positive or negative cash flow depending heavily on financing rate and down payment.

FAQ

What is a good cash flow on a rental property?

There is no universal amount. Consider risk, reserves, local conditions, financing, management time, taxes, and alternative uses of capital.

Does cap rate include the mortgage?

No. Cap rate is an unlevered property metric based on NOI before debt service.

What expenses should I include?

Consider property taxes, insurance, repairs, capital reserves, management, utilities paid by the owner, dues, licensing, landscaping, and turnover.

How much vacancy should I assume?

Use local historical evidence and a conservative allowance. Seasonal, student, short-term, and single-tenant properties can have different risk.

Does this calculate depreciation or income tax?

No. Tax treatment can be material and depends on basis, personal use, passive-activity rules, and individual circumstances.

Common mistakes

  • Omitting capital expenditure reserves for roof, HVAC and appliances.
  • Using zero vacancy in a market with seasonal turnover.
  • Confusing cap rate with cash-on-cash return; cap rate ignores financing.
  • Forgetting management fees when you will not self-manage.

Tips

  • Use market rent from comparable units, not the current owner's asking rent.
  • Budget vacancy, maintenance and capital expenditure as separate line items.
  • Compare cash-on-cash return with what the same cash earns elsewhere.
  • Re-run the numbers with a one percentage point higher rate before committing.

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Sources and editorial review

Educational estimates only; not personalized financial, tax, legal, lending, investment, or insurance advice.