Rental Property Cash Flow Calculator (2025)
Calculate the monthly and annual cash flow of any rental property after all expenses, mortgage, vacancy, and management fees.
Investment Returns
-5.44%
Cash-on-Cash Return
$3,261
Annual Cash Flow
9.60%
Gross Yield
Negative cash flow of -$272/mo — property relies on appreciation.
Analysis & insights
Your monthly expenses is 2,479.755, based on the inputs above. Loan and credit decisions compound over years. Small rate or term changes have outsized lifetime impact.
Calculation summary
Result derived from 3 inputs. Adjust any one to test sensitivity.
Risk & benchmark gauge
Current band
Moderate
Monthly Expenses: 2,479.755
Industry benchmarks
- Mortgage1,678
- Effective Rent$2,208
- Monthly Expenses2,480
- Monthly Cash Flow-272
- Annual Cash Flow-$3,261
- Cash On Cash-5.44
Key insights
Time + rate compound
In long-horizon money math, small changes in rate or time produce outsized changes in the final number. Try ±1% on the rate to see sensitivity.
Sensitivity testing
Adjust each input by ±10% to find the most impactful variable — that's the one to focus your real-world decisions on.
Recommended actions(4)
Test the realistic range of each input
High priorityTry the lowest and highest realistic value for each input. The spread of results is the range you should actually plan for — point estimates lie.
Impact: Reveals which inputs matter most and where uncertainty hides.
Compare against published benchmarks
Medium priorityWhatever you're calculating, there's likely an industry benchmark for it. Google "[topic] average" or "[topic] median" to sanity-check the result.
Save or download a copy
Medium priorityFor calculators that offer it, use "Download report (PDF)" to keep a snapshot. Otherwise screenshot the inputs + result before navigating away.
This tool is for educational purposes only and does not constitute financial, tax, or investment advice. Consult a qualified financial professional for advice specific to your situation.
What is Rental Property Cash Flow?
Cash flow is what remains each month after the rent has paid every bill, including the mortgage. It is the number that determines whether a rental property funds itself or quietly funds itself out of your salary.
It is also where optimistic analysis does the most damage. Subtracting a mortgage payment from rent produces an encouraging figure and omits roughly half the real costs. Vacancy, management, maintenance and capital replacement are not optional extras — they are certainties that arrive irregularly, and a property that only works when nothing goes wrong is a property that does not work.
The purpose of a careful cash-flow model is not pessimism. It is to know in advance which months will be negative, so that a boiler failure is a budgeted event rather than a crisis.
The formula — how to calculate Rental Property Cash Flow
- Effective rent
- = gross rent adjusted for expected empty periods — not the asking rent
- Operating expenses
- = tax, insurance, management, maintenance, capital reserve, utilities you pay, HOA
- Debt service
- = mortgage principal and interest. Unlike in a cap rate calculation, this IS included here
Cash flow includes financing; NOI and cap rate exclude it. The same property yields two different-looking answers depending on which question you are asking, and both are correct.
Step-by-step example
- 01A single-family rental purchased at $300,000 with 25% down ($75,000), so a $225,000 loan at 7% over 30 years.
- 02Mortgage principal and interest: $225,000 × [0.005833 × 1.005833³⁶⁰] ÷ [1.005833³⁶⁰ − 1] ≈ $1,497 per month.
- 03Market rent $2,200. Vacancy allowance at 8%: effective rent = $2,200 × 0.92 = $2,024.
- 04Operating expenses per month — property tax $300, insurance $125, management at 9% of collected rent $182, maintenance $110, capital reserve $110.
- 05Total operating expenses: $827.
- 06Cash flow = $2,024 − $827 − $1,497 = −$300 per month.
- 07The property loses $3,600 a year despite a 25% deposit and rent that comfortably exceeds the mortgage payment.
- 08Compare the naive calculation: $2,200 rent minus $1,497 mortgage = $703 "profit". The gap between $703 and −$300 is exactly the cost of the expenses that optimistic analysis omits.
The expenses that turn positive into negative
The example above is not unusual. In many markets, a property that appears strongly cash-flow positive on rent-minus-mortgage is negative once real costs are included.
Full expense checklist
| Expense | Typical allowance | Note |
|---|---|---|
| Vacancy | 5–10% of gross rent | Turnover always happens eventually |
| Property management | 8–10% of collected rent | Include even if self-managing |
| Maintenance | 5–10% of rent | Higher for older properties |
| Capital reserve | 5–10% of rent | Roof, HVAC, water heater, appliances |
| Property tax | Varies widely | Check whether the sale triggers reassessment |
| Insurance | Higher than owner-occupied | Landlord policies cost more than homeowner policies |
| Turnover costs | 1–2 months rent per turnover | Cleaning, paint, repairs, letting fees |
| HOA dues | Where applicable | Often excluded from listing figures |
Percentages are common underwriting conventions, not rules. Older properties and transient rental markets justify the upper end of each band.
Reserves are the difference between an investment and a liability
A single roof replacement can exceed two years of positive cash flow. Holding three to six months of full operating costs plus mortgage in reserve is what allows you to hold through a vacancy or a major repair rather than being forced to sell at the worst moment.
Why negative cash flow is not automatically a bad deal
Cash flow is one of four ways rental property produces returns, and focusing on it alone can be as misleading as ignoring it.
Principal paydown builds equity every month regardless of cash flow — your tenant is retiring your loan. Appreciation may add value, though it should never be assumed. And depreciation provides a substantial tax deduction: residential rental property is depreciated over 27.5 years, which shelters income that never actually left your pocket.
A property losing $300 a month in cash while paying down $250 of principal and generating a depreciation deduction is a materially different proposition from one simply losing $300. It may still be a poor investment — but the analysis has to include all four components.
The caution is that three of the four are illiquid. Equity and appreciation cannot pay a boiler bill. Negative cash flow must be funded from income every single month, which is why it is only defensible when you can comfortably sustain it.
- Cash flow —
- the only component that is liquid and immediate.
- Principal paydown —
- forced saving funded by the tenant; realised at sale or refinance.
- Appreciation —
- uncertain and market-dependent; never underwrite a deal on it.
- Tax benefits —
- depreciation over 27.5 years plus deductible expenses. Note that depreciation is recaptured and taxed on sale.
Screening rules and what they are actually worth
Investors use quick heuristics to filter listings before running full numbers. They are screening devices, not verdicts, and their usefulness has declined as prices have risen relative to rents in many markets.
The 1% rule holds that monthly rent should be at least 1% of purchase price — $3,000 monthly rent on a $300,000 property. In much of the country this now excludes almost everything, which tells you more about the rule than about the market.
The 50% rule assumes operating expenses excluding the mortgage consume roughly half of gross rent. On $2,200 rent that implies $1,100 of expenses against the $827 in our example, which is a reasonable sanity check — if your projected expenses are far below half of rent, something is probably missing.
Use these to decide what to analyse properly. Never use them to decide what to buy.
Model the vacancy month explicitly
Averaging vacancy into a monthly percentage hides how it actually arrives. An empty property produces zero rent while the mortgage, tax and insurance continue — a single vacant month typically costs more than three months of positive cash flow. Ask whether you could absorb two consecutive empty months, because eventually you will have to.
Key considerations
- Underwrite on effective rent after vacancy, never on asking rent.
- Include management at market rate even if you intend to self-manage.
- Separate maintenance from capital reserves; they fund different kinds of failure.
- Confirm whether the purchase triggers a property tax reassessment.
- Get a landlord insurance quote for the specific address rather than estimating.
- Hold three to six months of full costs in reserve before buying, not after.
- Model the deal at a higher vacancy rate and a lower rent to see where it breaks.
Common mistakes to avoid
- Calculating cash flow as rent minus mortgage, omitting roughly half the real costs.
- Assuming 100% occupancy, which no rental sustains indefinitely.
- Excluding management fees because you plan to self-manage.
- Treating maintenance and capital expenditure as the same reserve.
- Using the seller's property tax figure when a sale will trigger reassessment.
- Buying with no reserves, so the first major repair forces a distressed sale.
- Underwriting on expected appreciation rather than on the numbers as they stand today.
Frequently asked questions
Sources & references
Written and fact-checked by the CalcProLabs Editorial Team against IRS Publication 527 and standard rental underwriting practice. Read our calculation methodology and editorial policy.
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