Rental Property Cash Flow Calculator

Use monthly rent, realistic vacancy, operating reserves, and the actual financing you expect. Results are pre-tax planning estimates, not legal, tax, or investment advice.

Deal profile:

Choose a buy-and-hold starting pattern or keep Custom after editing.

Currency symbol:

Use $, EUR, GBP, RM, or another short symbol for your underwriting sheet.

Purchase price:

Enter the contract price or all-in acquisition price before closing costs and repairs.

Monthly rent:

Gross scheduled rent before vacancy, management, and reserves.

{{ currencyLabel }} / mo

Vacancy allowance: {{ formatPercent(vacancy_rate, 1) }}

Use a conservative local vacancy and turnover assumption.

Down payment: {{ formatPercent(down_payment_pct, 1) }}

Investment property loans often need more equity than owner-occupied loans.

Interest rate: {{ formatPercent(interest_rate, 2) }}

Use the investment-property note rate you can actually secure.

% / yr

Loan term:

Use 0 when modeling an all-cash purchase.

yrs

Property tax:

Annual tax estimate from the county, reassessment, or broker package.

{{ currencyLabel }} / yr

Insurance:

Use the landlord policy quote, not owner-occupied insurance unless that is the actual policy.

{{ currencyLabel }} / yr

HOA or fixed dues:

Use 0 if there are no recurring association dues.

{{ currencyLabel }} / mo

Maintenance reserve: {{ formatPercent(maintenance_pct, 1) }} of rent

Keeps routine repairs from overstating cash flow.

Management fee: {{ formatPercent(management_fee_pct, 1) }}

Use 0 for self-management only when you are deliberately valuing your own time elsewhere.

CapEx reserve: {{ formatPercent(capex_pct, 1) }} of rent

Model reserves separately so NOI is not inflated by deferred replacements.

Closing costs: {{ formatPercent(closing_cost_pct, 1) }}

Add lender, title, transfer, inspection, and acquisition fees paid out of pocket.

Initial repairs or rehab:

Use 0 for a stabilized turnkey property.

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Other monthly income:

Include only predictable recurring income.

{{ currencyLabel }} / mo

Owner-paid utilities:

Use monthly owner-paid utilities not reimbursed by tenants.

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Other operating expenses:

Keep debt payments out of this line so NOI remains property-level.

{{ currencyLabel }} / mo

Initial cash reserve:

Use 0 if reserves are tracked outside the acquisition cash stack.

Target cash-on-cash: {{ formatPercent(target_coc_pct, 1) }}

Set the yearly return target for your cash invested.

Target DSCR: {{ formatRatio(target_dscr) }}

Common lending screens often focus around 1.20 to 1.25, but requirements vary.

Stress rent change: -{{ formatPercent(stress_rent_drop_pct, 1) }}

Use 5-15% when testing soft rent comps.

Stress vacancy add-on: +{{ formatPercent(stress_vacancy_add_pct, 1) }}

Vacancy stress tests downtime, turnover, and slower collections.

Stress expense add-on: +{{ formatPercent(stress_expense_add_pct, 1) }}

Models insurance, repairs, tax, utility, or management cost pressure.

Stress rate add-on: +{{ formatPercent(stress_rate_add_pct, 2) }}

Use 0 if the loan rate is fixed and locked.

Money precision:

Whole units are usually best for an investor memo.

Metric	Value	Planning note	Copy
{{ row.metric }}	{{ row.value }}	{{ row.note }}

Line item	Monthly	Annual	Treatment	Copy
{{ row.item }}	{{ row.monthly }}	{{ row.annual }}	{{ row.treatment }}

Scenario	Cash flow	DSCR	Cash-on-cash	Signal	Copy
{{ row.scenario }}	{{ row.cashFlow }}	{{ row.dscr }}	{{ row.coc }}	{{ row.signal }}

Target	Required rent	Meaning	Copy
{{ row.target }}	{{ row.requiredRent }}	{{ row.meaning }}

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Rental cash flow is the monthly money left after a property collects rent, absorbs vacancy, pays operating expenses, and services any loan. It is a practical underwriting measure because a property can look attractive from purchase price or rent alone while still needing owner subsidy after taxes, insurance, repairs, reserves, management, and financing are counted.

Good rental analysis separates property performance from financing. Net operating income, or NOI, measures the property before debt service. Cash flow measures the investor's remaining pre-tax cash after debt service. Cap rate uses NOI and purchase price, so it can compare properties with different loan choices. Cash-on-cash return uses annual cash flow and cash invested, so it is sensitive to down payment, closing costs, initial repairs, and reserves.

Rental income waterfall diagram showing rent reduced by vacancy, operating expenses, debt service, and ending cash flow.

Vacancy deserves its own line because a rented unit rarely collects every scheduled dollar forever. Turnover time, concessions, uncollected rent, seasonal softness, and local vacancy rates can all reduce effective income. A small vacancy allowance can be reasonable for a stable property, but it can make a new lease-up or weak market look safer than it is.

Reserves are another common source of overconfidence. Routine maintenance covers smaller recurring repairs, while capital expenditure reserves cover longer-cycle replacements such as roofs, heating and cooling equipment, appliances, flooring, and exterior work. Leaving reserves out can turn a property with deferred maintenance into a positive-looking deal on paper.

Cash flow is still only a first-pass investment signal. It does not prove that the property is suitable, fairly priced, financeable, or tax efficient. Lease quality, tenant concentration, local rent rules, insurance availability, property condition, lender underwriting, and personal risk tolerance can all change the decision after the arithmetic looks acceptable.

How to Use This Tool:

Start with the rent roll and purchase terms, then tune the reserves, target tests, and downside assumptions.

Choose a Deal profile or keep Custom rental deal. Set the Currency symbol first if the estimate is not in dollars.
Enter Purchase price, Monthly rent, Vacancy allowance, Down payment, Interest rate, and Loan term. Use a loan term of 0 only for an all-cash case.
Add owner-paid expenses: Property tax, Insurance, HOA or fixed dues, Maintenance reserve, Management fee, CapEx reserve, owner-paid utilities, and other recurring operating costs.
Enter Initial repairs or rehab, closing costs, and cash reserve so Cash invested and Cash-on-cash return use the same out-of-pocket basis you expect.
Open Advanced to adjust Target cash-on-cash, Target DSCR, rent stress, vacancy stress, expense stress, rate stress, and money precision.
Review Deal Snapshot, Underwriting Ledger, Stress Table, Target Rent Table, and Monthly Cash Flow Bridge. Use JSON only when you need a structured copy of the assumptions and results.

If the summary says Needs valid deal terms, fix the validation message first. The calculation needs a purchase price above zero, at least one recurring income source, and a positive loan term unless the down payment is 100%.

Interpreting Results:

Monthly cash flow is the headline pre-tax result after vacancy, operating expenses, reserves, and debt service. A positive number does not mean the deal is strong. It must still be compared with Debt service coverage, Cash-on-cash return, and the downside rows.

Rental property output fields and interpretation cues
Output	What to check	Common false confidence
Net operating income	Property income after vacancy and operating expenses, before debt service.	NOI can look high when reserves or management costs are understated.
Debt service coverage	Annual NOI divided by annual debt service when debt is present.	A ratio below 1.00 means NOI does not cover modeled annual debt service.
Cash-on-cash return	Annual cash flow divided by down payment, closing costs, rehab, and reserve cash.	Low cash invested can inflate the percentage while leaving thin dollar cash flow.
Break-even occupancy	Occupied income share needed to cover expenses and debt service.	A value near or above 100% leaves little room for vacancy or collection loss.
Target rent rows	Rent needed for break-even cash flow, target cash-on-cash, target DSCR, and combined-stress break-even.	A target rent above local market rent is a pricing problem, not a calculator problem.

The verdict labels are screening cues. Subsidy risk means cash flow is negative. Debt shortfall means annual NOI is below annual debt service. Below target means cash flow is positive but the selected DSCR or cash-on-cash target is not cleared.

Before treating a positive result as decision evidence, compare the Stress Table with the base case. A small rent drop, higher vacancy allowance, expense increase, or rate increase can move a thin deal from positive cash flow to owner subsidy.

Technical Details:

Rental underwriting starts with gross scheduled income and then reduces it to effective gross income. Vacancy loss is calculated from gross scheduled income, so other recurring income is affected by the same vacancy allowance in this model. Management fee is calculated from effective gross income, while maintenance and CapEx reserves are percentages of rent.

NOI excludes debt service by design. That makes cap rate and DSCR comparable across loan choices. Cash flow then subtracts the monthly principal-and-interest payment, and cash-on-cash return uses the cash actually invested as the denominator.

Formula Core:

The core formulas keep income, expenses, financing, and return measures separate before they are recombined into the final verdict.

\begin{array}{lcl} gross scheduled income & = & monthly rent + other monthly income \\ effective gross income & = & gross scheduled income - vacancy loss \\ NOI & = & effective gross income - operating expenses \\ monthly cash flow & = & NOI - monthly debt service \\ monthly debt service & = & loan \times \frac{i \times {(1 + i)}^{n}}{{(1 + i)}^{n} - 1} \end{array}

In the loan formula, i is the monthly interest rate and n is the number of monthly payments. If the loan amount or term is zero, debt service is treated as zero. If the annual rate is zero but a loan term exists, the loan amount is divided evenly across the monthly payment count.

\begin{array}{lcl} DSCR & = & \frac{annual NOI}{annual debt service} \\ cap rate & = & \frac{annual NOI}{purchase price} \times 100 \\ cash-on-cash return & = & \frac{annual cash flow}{cash invested} \times 100 \\ break-even occupancy & = & \frac{operating expenses + debt service}{gross scheduled income} \times 100 \end{array}

Rental property verdict rules
Verdict	Rule	Meaning
Subsidy risk	Monthly cash flow < 0	Modeled rent does not cover expenses and debt service.
Debt shortfall	Annual debt service > 0 and DSCR < 1.00	NOI does not cover annual debt service.
Below target	DSCR is below target or cash-on-cash return is below target	Cash flow is positive, but the selected return screen is not cleared.
Unlevered income	Annual debt service <= 0	The property is modeled without debt service.
Meets targets	Cash flow is non-negative and selected return tests are cleared	The model clears its current screens, subject to the assumptions entered.

Target rent rows are solved by repeatedly testing higher and lower rent values until the selected condition is just met. This is useful for rent sensitivity, but it does not prove that a market can support that rent or that the property condition justifies it.

Responsible Use Note:

The result is an educational underwriting estimate, not financial, tax, legal, lending, or investment advice. Confirm rent, taxes, insurance, financing, vacancy, repairs, reserves, local rules, and tax treatment with qualified professionals before making an offer or committing capital.

Worked Examples:

A duplex profile with a $420,000 purchase price, $3,200 monthly rent, $100 other monthly income, 7% vacancy, 25% down, a 7.25% loan, and the default reserve assumptions produces roughly $1,592 monthly NOI. The modeled debt service is about $2,149, so Monthly cash flow is about -$556 and the verdict is Subsidy risk.

A cash purchase changes the reading. With no debt service, Debt service coverage becomes n/a, and the deal should be read through Cap rate, Cash-on-cash return, and dollar cash flow. An unlevered property can still disappoint if the cap rate is low for the risk and local alternatives.

A boundary case appears when Debt service coverage is just under the selected target. Positive cash flow may still receive Below target because the target DSCR or cash-on-cash return is not cleared. Review the Target Rent Table to see whether a realistic rent increase would fix the gap.

A troubleshooting case starts with a zero purchase price, no recurring income, or a financed deal with a zero loan term. The validation message names the missing assumption, and result tabs should not be used until those fields are corrected.

FAQ:

Is NOI the same as cash flow?

No. Net operating income is income after vacancy and operating expenses, before debt service. Monthly cash flow subtracts the modeled principal-and-interest payment after NOI.

Why can cash flow be positive while the verdict says Below target?

The verdict also checks Target DSCR and Target cash-on-cash. A property can produce positive dollar cash flow and still miss one of those selected screens.

Where do repairs and reserves belong?

Routine repairs belong in Maintenance reserve. Long-cycle replacements belong in CapEx reserve. Up-front work before stabilization belongs in Initial repairs or rehab.

Why are no results shown after I edit the loan fields?

A financed deal needs a Loan term greater than zero. Use a 100% down payment and a zero loan term only when modeling an all-cash purchase.

Glossary:

Gross scheduled income: Monthly rent plus recurring other income before vacancy.
Effective gross income: Gross scheduled income after the vacancy allowance is subtracted.
Net operating income: Property income after vacancy and operating expenses, before debt service.
Debt service coverage: Annual NOI divided by annual debt service when a loan is modeled.
Cash-on-cash return: Annual cash flow divided by the modeled cash invested.
Break-even occupancy: The occupied income share needed to cover operating expenses and debt service.

References:

Publication 527, Residential Rental Property, Internal Revenue Service, 2025.
Commercial Real Estate Lending, Office of the Comptroller of the Currency, March 2022.
Debt Service Coverage Ratio, Fannie Mae Multifamily Guide.

Rental Property Cash Flow Calculator

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How to Use This Tool:

Interpreting Results:

Technical Details:

Formula Core:

Responsible Use Note:

Worked Examples:

FAQ:

Glossary:

References:

Rental Property Cash Flow Calculator

Current deal signal

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Introduction:

How to Use This Tool:

Interpreting Results:

Technical Details:

Formula Core:

Responsible Use Note:

Worked Examples:

FAQ:

Glossary:

References: