Rental Cash Flow Calculator

Estimate monthly and annual rental cash flow with full income and expense breakdowns — see exactly where every dollar goes before debt service.

Currency:

Cash Flow Inputs

Monthly income vs monthly expenses including mortgage

Monthly Rent

Other Monthly Income

Vacancy Rate

Management Fee

% of rent

Property Tax (Annual)

Insurance (Annual)

HOA (Monthly)

Maintenance (Annual)

Utilities (Monthly)

Other Expenses (Annual)

Mortgage Payment (Monthly)

P+I only — taxes and insurance go in their own fields

About the Rental Property Calculator

A rental property combines four wealth engines into a single asset: monthly rental cash flow, long-term appreciation, mortgage principal paydown by your tenant, and tax advantages from depreciation. Each one is small on its own — together they can compound into substantial wealth over a 10–30 year holding period. The challenge is that real estate is also operationally complex, illiquid, and locally sensitive: a great deal in Cleveland is a terrible deal in San Francisco, and vice versa. This calculator forces you to underwrite all four engines together, with realistic expense assumptions, before you sign anything.

How Rental Property Analysis Works

Underwrite the deal first

Plug in the actual asking price, your real down payment, current local rates, and conservative rent for the unit. Don't use seller-supplied 'pro-forma' rents that assume full occupancy and zero turnover — those numbers exist to sell the property, not to underwrite it.

Stress-test the assumptions

Bump vacancy from 5% to 10%, drop rent growth from 3% to 1%, increase maintenance from $2,000 to $4,000. If the deal still works in the stressed scenario, you've got margin. If a 100-bps vacancy bump turns it negative, you're buying yield without a cushion.

Three Ways to Use This Calculator

Single-family rental

Evaluate a 3-bed/2-bath house at $300,000, $1,800/mo rent, 20% down, and 30-year financing. Watch cap rate, cash-on-cash, and DSCR cluster around the typical SFR ranges.

Small multifamily (2–4 unit)

Model a duplex by entering combined rent across units and a slightly higher operating-expense ratio (multi-tenant maintenance scales faster than SFR).

BRRRR-style value add

Use the repair-costs and emergency-reserve fields to capture the rehab and reserve cushion, then compare cash-on-cash before and after a refinance.

Underwriting Best Practices

Use realistic vacancy (5%–10%) — don't assume year-round occupancy.
Set aside 1%–2% of property value annually for maintenance + capex reserves.
Stress-test rent growth at 0% — appreciation should justify the deal on its own.
Compare cap rate to comparable sales in the same zip code, not a national average.
Verify DSCR clears 1.25 even after one full month of vacancy.
Treat property management fees as a real expense even if you self-manage — your time has value.

Why Conservative Underwriting Matters

Rental property analysis built on optimism is the single most common reason real-estate investors fail. The IRS lets you take depreciation, leverage lets you control 4× the assets you could buy in cash, and rent payments build equity automatically — but none of that helps if vacancy creeps up, a furnace dies, or a tenant stops paying. Conservative underwriting up front is how seasoned investors stay profitable through every market cycle.

Tricky Cases Investors Get Wrong

Pro-forma vs actual rent

Sellers and brokers love to quote 'pro-forma' (market-rate, fully-occupied) numbers. Always re-underwrite using last-12-months actual collected rent and at least 5% vacancy.

Capex is not maintenance

Replacing a roof, HVAC, or water heater is capital expenditure, not monthly maintenance. Reserve separately or your true cash flow is overstated by hundreds of dollars per month.

Cap rate isn't return

Cap rate ignores financing. A 5% cap deal can produce 12% cash-on-cash with leverage — or destroy equity if rates climb. Use cap rate to compare properties; use cash-on-cash + IRR to evaluate yours.

Core Formulas

Cap Rate

NOI ÷ Property Value × 100

NOI

Effective Rent − Operating Expenses (pre-debt)

Cash-on-Cash

Annual Cash Flow ÷ Total Cash Invested × 100

DSCR

NOI ÷ Annual Debt Service

GRM

Property Value ÷ Annual Gross Rent

ROI

Total Profit ÷ Total Cash Invested × 100

Equity (year N)

Property Value − Loan Balance

Common Mistakes

Ignoring vacancy and treating gross rent as effective income.
Forgetting capex reserves and treating maintenance as the only repair line.
Using national cap-rate averages instead of zip-code comps.
Assuming optimistic rent growth (5%+) over a 20-year hold.
Underestimating closing costs, financing fees, and reserves at acquisition.
Not pricing in property-management cost when self-managing.

Methodology & Sources

Formulas in this calculator follow standard U.S. residential real-estate underwriting conventions. Depreciation defaults to 27.5-year straight-line on 80% of purchase price (the IRS residential schedule). Cap rate, NOI, DSCR, cash-on-cash, ROI, and IRR are calculated exactly as taught in commercial real-estate underwriting curricula. Investment-score weights reflect general industry guidance, not personal financial advice — every market and deal is different.

Frequently Asked Questions

What is a good cap rate for rental property?

Cap rates vary by market, but most U.S. residential investors target 5%–10%. Class A trophy properties in coastal cities often trade at 3%–5%, mid-tier stabilized assets at 5%–7%, and value-add / Class C properties at 7%–10%+. Higher cap rates usually signal higher operational risk — verify vacancy, deferred maintenance, and tenant quality before treating a high cap rate as a bargain.

What is NOI (Net Operating Income)?

Net Operating Income is gross rental income minus vacancy / bad-debt losses and all operating expenses (taxes, insurance, maintenance, management, utilities, HOA, landscaping, other), but BEFORE mortgage debt service, depreciation, and income taxes. NOI is the input to cap rate (NOI ÷ price) and DSCR (NOI ÷ annual debt service).

What is cash-on-cash return?

Cash-on-cash return is annual pre-tax cash flow ÷ total cash invested (down payment + closing costs + repairs + reserves). It measures the return on the actual cash you put in, ignoring loan amortization and appreciation. Most rental investors target at least 6%–8%.

What is IRR in real estate?

Internal rate of return (IRR) is the annualized return that makes the net present value of every cash flow — initial outlay, year-by-year rental cash flow, and net sale proceeds — equal zero. IRR captures both cash flow AND appreciation in a single, time-weighted number. A 10%–15% projected IRR is competitive with public equity benchmarks.

What is DSCR and what's a safe level?

Debt Service Coverage Ratio is NOI ÷ annual mortgage debt service. A DSCR of 1.00 means rent exactly covers the mortgage; 1.25 is the typical commercial lender minimum; 1.50+ leaves comfortable margin for vacancies, repairs, and rate hikes. Below 1.0 means the property loses money before factoring in capital expenses.

How do I calculate rental cash flow?

Cash flow = (effective rental income) − (operating expenses) − (mortgage payment). Effective rental income = gross rent × (1 − vacancy rate − bad-debt rate). Operating expenses include property tax, insurance, HOA, maintenance, utilities you pay, management fees, landscaping, and an 'other' bucket for irregular expenses. Mortgage payment is principal + interest only — taxes and insurance escrowed by the lender should already be in operating expenses.

Is appreciation included in ROI?

It depends on which ROI you mean. Cash-on-cash return excludes appreciation entirely. Total ROI = (total cash flow + net sale proceeds − total cash invested) ÷ total cash invested, which captures appreciation, loan paydown, and cash flow together. IRR includes all three on a time-weighted basis. Always check which definition a quoted ROI is using.

What expenses should I include?

Always include: property tax, insurance, maintenance (1%–2% of value/yr is a reasonable starting reserve), property management (8%–12% of rent if outsourced), HOA, utilities you pay (water/trash/sewer in most markets), turnover/leasing costs, vacancy reserve, and capital expenditure reserve (5%–10% of rent). Excluding capex and management is the most common reason pro-formas look better than reality.

How much vacancy should I assume?

5%–8% is a reasonable national starting assumption. Strong landlord-friendly markets with high demand may sustain 2%–4%; soft markets, college towns, or seasonal areas can run 10%+. Local property managers and MLS data on average days-on-market are the best sources for a realistic number.

Is positive cash flow always a good investment?

No. Positive cash flow is necessary but not sufficient. Compare your total return (cash flow + appreciation + loan paydown) against alternatives like an index fund, REIT, or bonds. A property that cash-flows $100/month but ties up $80,000 and barely keeps up with inflation may underperform a passive 7% S&P 500 return. Look at IRR, ROE, and the opportunity cost of your capital — not just monthly cash flow.