Does cash flow here include loan principal as well as interest?

Yes. Debt service in this calculator is principal and interest together. Net cash flow is after P&I, so it reflects the true monthly cash leaving or entering your bank account before taxes.

How should I handle CapEx reserves?

You can either include a monthly CapEx reserve in operating expenses for a more conservative view or track it separately. Many investors add a fixed dollar amount per unit per month to approximate long-term replacements for roofs, HVAC, and interiors.

Should I enter monthly or annual numbers?

Enter monthly amounts for rent, other income, expenses, and debt service. The calculator automatically multiplies by 12 to show annualized NOI and cash flow so you can compare with yearly pro formas.

What is the difference between NOI and cash flow?

NOI is income before financing—it subtracts operating expenses but not debt service. Net cash flow subtracts debt service from NOI, so it shows the impact of leverage and is the figure most investors care about for day-to-day cash performance.

Does this calculator account for taxes on cash flow?

No. All figures are pre-tax. Actual after-tax results depend on your broader tax situation, interest and expense deductions, and depreciation. Use the outputs here as inputs to separate tax planning or discuss them with a tax professional.

finance calculator

Rental Cash Flow Calculator

Calculate monthly and annual rental cash flow by accounting for vacancy, operating expenses, and debt service.

Results

Gross monthly income: $2,350
Vacancy loss (monthly): $118
Effective gross income (monthly): $2,233
Operating expenses (monthly): $600
NOI (monthly): $1,633
NOI (annual): $19,590
Debt service (monthly): $1,200
Cash flow (monthly): $433
Cash flow (annual): $5,190

Overview

Cash flow is the lifeblood of a rental—yet it is easy to misjudge when you only look at rent and a handful of obvious bills. This rental cash flow calculator walks through the full stack from gross scheduled rent to net cash flow after vacancy, operating expenses, and debt service, showing both monthly and annual results.

Use it to sanity-check deals before making offers, to compare financing options, or to understand why a property that “should cash flow” on paper might actually be negative once you account for realistic vacancy and expenses.

How to use this calculator

Enter the current or projected monthly rent for the unit or property. For multi-unit buildings, use the total scheduled rent for all units.
Add other monthly income such as parking, storage, pet rent, laundry, or utility bill-backs (RUBS). If income is seasonal, enter a realistic monthly average based on annual totals.
Set a vacancy allowance percentage that reflects your market, tenant profile, and asset type. Many investors model at least 5–8% even in strong markets.
Enter your total monthly operating expenses, including property taxes, insurance, repairs and maintenance, property management, landlord-paid utilities, HOA dues, and routine upkeep.
Enter your monthly principal and interest payment (debt service). If taxes and insurance are escrowed by the lender, keep those items in operating expenses so they are not double-counted.
Review the output: gross income, vacancy loss, EGI, NOI, and net cash flow per month and per year. Adjust inputs to test different rent levels, expense assumptions, or loan terms.
Save or export a few scenarios—optimistic, base case, and conservative—so you can compare how resilient the deal is under different assumptions.

Inputs explained

Monthly rent: The total scheduled rent you expect to collect if the unit or property is fully occupied and all tenants pay. For multi-unit properties, sum all unit rents into a single monthly figure.
Other monthly income: Recurring income beyond base rent, such as parking fees, storage, pet rent, laundry machines, utility bill-backs (RUBS), or amenity fees. Exclude one-time charges, application fees, and security deposits.
Vacancy allowance (%): A percentage haircut applied to gross income to reflect lost rent from vacancy and non-paying tenants. Use market-based assumptions—stable markets may justify 5–8%, while more volatile or seasonal markets may warrant higher rates.
Operating expenses (monthly): All recurring costs required to operate the property before financing: property taxes, insurance, repairs and maintenance, lawn/snow, property management, landlord-paid utilities, HOA dues, and routine servicing. Exclude loan principal and interest, which are captured in the debt-service input.
Debt service (monthly P&I): Your monthly principal and interest payment on the mortgage or private loan. If your lender escrows taxes and insurance, keep those amounts in operating expenses so they are not double-counted.

How it works

You enter scheduled monthly rent, any other recurring monthly income (such as parking or pet rent), an allowance for vacancy and credit loss, monthly operating expenses, and monthly debt service.

The calculator first computes gross monthly income as: Gross income = Monthly rent + Other monthly income. This is the income you would collect if the property were fully occupied and everyone paid on time.

Next it applies your vacancy allowance to estimate typical lost income: Vacancy loss = Gross income × Vacancy%. Subtracting vacancy from gross yields Effective gross income (EGI), a more realistic view of what you actually collect.

Operating expenses—taxes, insurance, repairs, maintenance, management, and landlord-paid utilities—are subtracted from EGI to get Net operating income (NOI). NOI is income before financing and is a key metric for valuation and loan underwriting.

Debt service (your monthly principal and interest payment) is then subtracted from NOI to arrive at net cash flow. Positive cash flow means money left over after debt service; negative cash flow indicates that the property requires a cash subsidy each month.

For each stage of the calculation, the tool also annualizes results by multiplying monthly figures by 12 so you can compare them with annual pro formas, lender DSCR requirements, and cap-rate-based valuations.

All calculations are based on the numbers you provide, so conservative inputs and realistic assumptions are critical for useful results.

Formula

We follow standard income-statement style rental math.
Gross income = Monthly rent + Other monthly income
Vacancy loss = Gross income × Vacancy%
Effective gross income (EGI) = Gross income − Vacancy loss
Net operating income (NOI) = EGI − Operating expenses
Net cash flow = NOI − Debt service
Annual figures = Monthly result × 12

When to use it

Quickly underwriting potential rental purchases to see whether they are likely to produce positive monthly and annual cash flow before you write an offer.
Stress-testing an existing rental by increasing vacancy assumptions or operating expenses to see how resilient your cash flow is under less favorable conditions.
Comparing different financing options—such as higher leverage vs lower rates—by adjusting the monthly debt-service input and seeing how net cash flow changes.
Evaluating whether a rent increase, value-add renovation, or amenity change is likely to materially improve cash flow after accounting for added expenses and vacancy risk.
Feeding outputs such as EGI, NOI, and net cash flow into other analyses like cap rate calculations, DSCR tests for lenders, and cash-on-cash return models.

Tips & cautions

Be honest and conservative with vacancy and expenses; underestimating either is one of the most common reasons investors are surprised by weak cash flow after closing.
Include professional management costs even if you plan to self-manage at first—this gives you a more realistic view of the property’s economics and preserves flexibility to hire management later.
Build routine repair and maintenance reserves into operating expenses rather than assuming major items will somehow pay for themselves; roofs, HVAC, and turnovers all impact long-term cash flow.
If income or expenses are highly seasonal (for example, student housing or vacation rentals), work from annual totals and divide by 12 to get a realistic average monthly figure.
Use the annualized outputs to compare multiple properties on an apples-to-apples basis and to sanity-check broker pro formas, which may assume lower expenses or vacancy than you are comfortable with.
Rerun the calculator after major changes such as refinances, significant tax reassessments, or large rent increases so your cash-flow picture stays current.
Provides a static monthly snapshot based on your inputs; it does not model rent growth, expense inflation, lease-up periods, or one-time capital projects over multiple years.
Does not explicitly separate capital expenditures (CapEx) from operating expenses; you should decide whether to include a monthly CapEx reserve in the operating-expense input.
Ignores income taxes, depreciation, and other tax benefits or costs. After-tax cash flow will differ and depends on your broader tax situation.
Assumes a single blended vacancy rate and uniform collection performance; individual unit-level issues or unusual tenant situations are not modeled.
Results depend heavily on the quality of your inputs; optimistic rent assumptions or understated expenses can make weak deals look better than they are in practice.

Worked examples

Solid positive cash flow on a single-family rental

Assume monthly rent of $2,200 and other income of $150 from parking, for a gross income of $2,350.
Use a 5% vacancy allowance: Vacancy loss ≈ $2,350 × 0.05 = $117.50, leaving EGI ≈ $2,232.50.
Enter operating expenses of $600 per month (taxes, insurance, maintenance, management, and utilities). NOI ≈ $2,232.50 − $600 = $1,632.50 per month, or about $19,590 per year.
With monthly debt service of $1,200, net cash flow ≈ $432.50 per month and about $5,190 per year.
Interpretation: this property produces a modest but positive cushion after debt service; you could compare the annual cash flow to your total cash invested to estimate cash-on-cash return.

Thin cash flow after higher expenses and vacancy

Assume monthly rent of $1,800 with no other income. Gross income is $1,800.
A vacancy allowance of 8% yields a vacancy loss of $144, so EGI = $1,656.
Operating expenses of $650 per month (higher taxes and an older property) give NOI = $1,006 per month.
With monthly debt service of $950, net cash flow is only about $56 per month, or roughly $672 per year.
Interpretation: even though the deal appears to cash flow, the margin is very thin. A few extra repairs or slightly higher vacancy could easily push it into negative territory.

Testing the impact of financing changes

Start with the first example’s numbers but increase debt service from $1,200 to $1,400 to reflect a higher interest rate or shorter amortization.
Recalculate: NOI remains about $1,632.50 per month, but net cash flow drops to roughly $232.50 per month.
Annual cash flow shrinks from about $5,190 to about $2,790.
Interpretation: small changes in rate and amortization can meaningfully reduce cash flow; this helps you see how sensitive a deal is to financing terms before you lock in a loan.

Deep dive

Use this rental cash flow calculator to move from gross scheduled rent to net cash flow after vacancy, operating expenses, and debt service, with both monthly and annual views.

Enter rent, other income, vacancy allowance, operating expenses, and debt service to see effective gross income (EGI), net operating income (NOI), and net cash flow in one place.

Underwrite single-family rentals, small multifamily properties, or house hacks quickly by testing different rent, expense, and financing scenarios.

Combine the outputs with cap rate, DSCR, and cash-on-cash return calculators to build a complete rental investment analysis.

Use conservative assumptions and multiple scenarios so your projected cash flow is robust to vacancies, unexpected repairs, and interest-rate changes.

FAQs

Does cash flow here include loan principal as well as interest?: Yes. Debt service in this calculator is principal and interest together. Net cash flow is after P&I, so it reflects the true monthly cash leaving or entering your bank account before taxes.
How should I handle CapEx reserves?: You can either include a monthly CapEx reserve in operating expenses for a more conservative view or track it separately. Many investors add a fixed dollar amount per unit per month to approximate long-term replacements for roofs, HVAC, and interiors.
Should I enter monthly or annual numbers?: Enter monthly amounts for rent, other income, expenses, and debt service. The calculator automatically multiplies by 12 to show annualized NOI and cash flow so you can compare with yearly pro formas.
What is the difference between NOI and cash flow?: NOI is income before financing—it subtracts operating expenses but not debt service. Net cash flow subtracts debt service from NOI, so it shows the impact of leverage and is the figure most investors care about for day-to-day cash performance.
Does this calculator account for taxes on cash flow?: No. All figures are pre-tax. Actual after-tax results depend on your broader tax situation, interest and expense deductions, and depreciation. Use the outputs here as inputs to separate tax planning or discuss them with a tax professional.

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Cap Rate Calculator

Calculate rental property cap rate from NOI and property value for quick deal screening.

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DSCR Calculator

Calculate debt service coverage ratio (DSCR) from NOI and annual debt service to check lender thresholds.

This rental cash flow calculator is a simplified educational tool. It does not model multi-year projections, tax impacts, or all possible expense categories, and it relies entirely on the accuracy of the numbers you enter. It is not financial, tax, or investment advice. Always perform detailed due diligence and consult qualified professionals before making purchase or financing decisions.