Rental Property Cash Flow Calculator
Compute monthly cash flow, NOI, cap rate, and cash-on-cash return for any rental property. Tests against the 1% and 50% rules. Free, no signup.
Rental Property Cash Flow Calculator
Full BiggerPockets-style rental analyzer. Enter purchase price, financing terms, gross rent, and operating costs. Returns monthly cash flow, NOI, cap rate, cash-on-cash, and tests against the classic 1% and 50% rules of thumb.
Rules-of-thumb checks
How to Use the Rental Cash Flow Tool
Pull realistic rent comps
Use Zillow Rent Zestimate + Rentometer + 3 active listings within ¼ mile of the same bed/bath count. Newcomer mistake: anchoring on listed rent rather than rent-comp data. Be conservative — the wrong rent assumption breaks every downstream number.
Set reserves honestly
The percentages here are investor rules of thumb, not measured averages: maintenance 5-10% of rent (newer property low end, older high), CapEx 5-10% of rent (roof, HVAC, water heater amortization), vacancy 5-8% in stable markets and more in turnover-heavy ones, property management 8-10% if you outsource — or 0 if you self-manage, counting your own time as opportunity cost.
Check against the 1% and 50% rules
1% Rule: monthly rent ≥ 1% of purchase price. Hard to find in 2026 except in low-cost Midwest/South markets. 50% Rule: total operating expenses should be ≤ 50% of gross rent. These are screening filters — properties that fail both are usually negative cash flow at typical financing.
Target cash-on-cash, not cap rate alone
Cap rate is the unlevered yield. Cash-on-cash includes mortgage leverage and is the actual return on dollars in. A common residential target is 8-12% CoC; the verdict line uses 10% as "strong" and 6% as "solid". Below that you're essentially betting on appreciation rather than current cash flow.
Rental Property Math — The Numbers That Decide a Deal
The Four Numbers That Matter
Rental real estate is a numbers business. The four metrics that matter most: NOI (Net Operating Income — gross rent minus all operating expenses, BEFORE mortgage), cap rate (NOI divided by purchase price, the unlevered yield), cash-on-cash return (annual cash flow divided by total cash invested, AFTER mortgage), and GRM (Gross Rent Multiplier — price divided by annual gross rent, the inverse of cap rate for quick screening). Each tells a different story. NOI is what the property earns regardless of how you finance it. Cap rate is what you'd earn paying cash. Cash-on-cash is the actual leveraged return. GRM is the fastest way to screen a list of properties before doing the full analysis.
Most rookie mistakes are in the operating expense column. The standard "PITI + maintenance" framing undercounts by 30-50% of true long-run expense. Real operating expenses include: property taxes, insurance, HOA, a vacancy reserve, a maintenance reserve, a CapEx reserve (roof, HVAC, appliances), property management (include your own time even if self-managing), utilities IF landlord-paid, accounting + legal — the tool's default reserve percentages are common rules of thumb, so replace them with your own figures where you have them. A "PITI breakeven" property with no reserves is almost always negative cash flow over a 10-year hold.
The 1% and 50% Rules — Useful Screens, Not Decision Rules
The 1% Rule: monthly rent should be at least 1% of purchase price. A USD 200K property should rent for at least USD 2,000/month. It is easier to satisfy where prices are low relative to rents, which today means mostly Midwest and Southeast markets. The 50% Rule: total operating expenses (NOT including mortgage) should be roughly 50% of gross rent. Combined, they say "if a property passes both, cash flow at typical financing is usually positive." Properties failing both rarely cash flow without substantial down payment. Properties that pass one but fail the other warrant deeper analysis — the rules are screening heuristics, not investment decisions.
Cap rates move inversely with price: high-cost coastal metros trade at the lowest cap rates because buyers pay for expected appreciation, while Rust Belt and rural markets trade at the highest. Investors targeting double-digit cash-on-cash typically need either lower-cost markets, value-add rehabs (the BRRRR strategy), or alternative-use cases (short-term rental, house hacking).
"A property looks great until you fully load the operating expenses. On the USD 2,800 rent in the example above, 'PITI + 5% maintenance' reserves USD 140 a month; '8% maintenance + 8% CapEx + 5% vacancy + 8% management' reserves about USD 810 — a USD 670 swing, enough to flip cash flow from positive to negative."
Tax Treatment That Boosts Real Returns
Cash-on-cash isn't the full story — US rental real estate offers significant tax advantages that boost the effective return. Depreciation: 27.5-year straight-line on residential, deducted from rental income, creating "paper losses" that offset cash flow. A USD 250K property (improvement value, NOT including land) generates ~USD 9,000/year of depreciation. For a typical leveraged rental, this often zeros out the taxable income. 1031 exchanges defer capital gains tax indefinitely when you sell + replace with another investment property. Mortgage interest is fully deductible against rental income. Cost segregation studies can accelerate depreciation on commercial and short-term-rental properties. For investors in high tax brackets, these advantages add materially to the after-tax return on top of the CoC figure — how much depends on your bracket and how much of the price is building rather than land.
The 1% Rule, the 50% Rule, and why NOI excludes the mortgage
NOI = effective gross income − operating expenses (NOT including mortgage). Cap rate = NOI ÷ purchase price.
The 1% Rule: monthly rent should be at least 1% of purchase price. A screening heuristic, easiest to meet where prices are low relative to rents.
The 50% Rule: opex should be ≤ 50% of gross rent. Combined with 1% Rule, these screen most positive-cashflow deals.
Cash-on-cash = (NOI − annual debt service) ÷ (down payment + rehab + closing). It is the levered return; cap rate is the unlevered one.
Conventional investor down payment: Fannie Mae's eligibility matrix allows up to 85% LTV on a one-unit investment purchase (15% down); 2–4 units and refinances require more.
Investor mortgage rates run above owner-occupied rates because Fannie Mae and Freddie Mac charge investment-property loan-level price adjustments on top of the base price.
Depreciation: residential rental buildings are written off over 27.5 years straight-line (IRS Publication 527); land is never depreciable. USD 250K of building = ~USD 9,100/yr.
1031 exchange: defers capital gains when selling + replacing with another investment property. Identify within 45 days, close within 180 (IRC §1031(a)(3)).
GRM (gross rent multiplier) = price ÷ gross annual rent — the quickest screen for a list of properties before running the full analysis.
Census Rental Housing Finance Survey 2021: individual investors own about 70% of US rental properties but only 38% of rental units — the big buildings belong to LLCs, partnerships and REITs.
Frequently Asked Questions
- Depends on market and property type. Class-A urban: 4-6%. Class-B suburban: 6-8%. Class-C value-add: 8-12%. Coastal high-appreciation markets (SF, NYC, Boston) typically trade at lower cap rates because investors price in expected appreciation. Sun Belt and Rust Belt offer higher cap rates with lower appreciation. There's no "right" cap rate — match your strategy (cash flow vs appreciation) to the market.
- Cap rate is the UNLEVERED return — what you'd earn if you paid all cash. Cash-on-cash is the LEVERED return — actual cash flow divided by actual cash invested (down payment + closing + rehab). Cash-on-cash is typically higher because leverage amplifies returns. Use cap rate to compare properties; use cash-on-cash to compare to your own opportunity cost of capital.
- Conventional investment property: 20-25% down minimum. Many lenders prefer 25%+ for the better rate. FHA + VA loans require owner occupancy — can't be used for pure rentals. House-hacking (live in one unit, rent the others in a 2-4 unit) qualifies for owner-occupied 3.5% (FHA) or 5% (conventional) down — the highest-leverage entry point for first-time rental investors. Commercial multifamily (5+ units) often requires 30-35% down.
- In order of frequency: (1) CapEx — the eventual roof, HVAC, water heater, exterior paint cost USD 25-50K every 10-20 years. Without a reserve, single events wipe out years of cash flow. (2) Vacancy — even great properties have 3-5% turnover; expect 1 month of vacancy every 2-3 years. (3) Maintenance — actual maintenance averages 1-2% of property value annually, much higher than rookie estimates. (4) Property management — even if you self-manage, your time is worth something. (5) Lawn care, snow removal, exterior maintenance if your local law makes those landlord responsibilities.
- Residential rental property is depreciated over 27.5 years (commercial: 39). The IRS lets you deduct 1/27.5 of the IMPROVEMENT value (building, NOT land) each year as a non-cash expense against rental income. A USD 350K property with USD 250K improvement value = ~USD 9K/year depreciation deduction. For a typical leveraged rental, this often zeros out the taxable income even though the property is generating positive cash flow. Depreciation must be "recaptured" when you sell (taxed at 25% federal) UNLESS you do a 1031 exchange to defer.
- Section 1031 of the IRC: defer capital gains tax when you sell an investment property AND replace it with another investment property of equal-or-greater value. Strict timing: 45 days to identify replacement, 180 days to close. Must use a qualified intermediary (QI) — you can't touch the funds. The deferred tax compounds — you can keep 1031'ing for decades and only owe the tax at final sale (or "step up" the basis to fair market value on inheritance). Most-used real-estate tax strategy for serious investors.
- Common practice for liability protection. LLC isolates the property's liabilities (lawsuit, accident, debt) from your personal assets. Trade-offs: forming + maintaining the LLC costs USD 100-500/year per state; mortgage transfer to LLC after closing can trigger "due on sale" clause (rare in practice but legally possible); some states require separate property insurance policy in LLC name. Most investors with 3+ properties use either LLCs or umbrella liability insurance (USD 1-2M coverage for USD 200-500/year — easier and often equivalent protection for residential rentals).
- Population growth + job growth + landlord-friendly laws + good price-to-rent ratio. Sun Belt cities (Austin, Charlotte, Tampa, Phoenix, Nashville, Raleigh) have been popular 2020-2024 due to all four factors. Avoid heavy-regulation cities (rent control: SF, NYC, LA portions, Portland, Seattle) for new investments. ATTOM Data + Roofstock publish market reports ranking US cities by rental investment metrics annually. Most successful investors pick 1-2 markets and develop deep local knowledge rather than buying scattered single properties nationally.
- Different business — higher revenue per night but with seasonality, cleaning costs, platform fees, and operating complexity, so a much larger share of gross revenue goes to operating expenses than in a long-term rental. Use the dedicated Airbnb ROI Calculator for STR-specific math. Many cities have restricted or banned STR — check local STR regulations BEFORE buying with that strategy.
- Yes — no US citizenship or residency required. Foreign investors typically need a larger down payment than residents, an ITIN (Individual Taxpayer Identification Number) for tax filing, and a US-based property manager; foreign-national mortgages exist but at higher rates and lower LTVs. US rental income is subject to US federal income tax (Form 1040-NR) — 30% withholding on the gross rent unless you elect under IRC §871(d) to treat it as effectively connected income and be taxed on the net. FIRPTA withholding (15% of the gross price, IRC §1445) applies when selling. Consult a US tax CPA with cross-border experience before purchase.
Method & sources
How it computes
Effective gross income = rent×12 − vacancy%; operating expenses = property tax + insurance + HOA×12 + maintenance% and CapEx% of gross rent + management% of effective income + utilities×12; NOI = EGI − opex; cap rate = NOI ÷ price; annual cash flow = NOI − 12 × level mortgage payment; cash-on-cash = cash flow ÷ (down + rehab + closing); GRM = price ÷ gross annual rent; 1% rule = rent ÷ price ≥ 1%; 50% rule = opex ÷ gross rent ≤ 50%.
What this tool implements
- NOI excludes debt service (standard appraisal-institute definition); cap rate is unlevered, cash-on-cash is levered
- Reserves (vacancy, maintenance, CapEx, management) are user inputs with rule-of-thumb defaults, labelled as heuristics
- Verdict thresholds: ≥10% CoC 'strong', ≥6% 'solid', >0 'marginal'
- US tax facts cited: 27.5-year residential depreciation (IRS Pub 527), §1031 45/180-day rules, §1445 FIRPTA 15%, §871(d) net election
Sources
- irs.gov — publications
- law.cornell.edu
- census.gov — rhfs.html
- Kellison SG. The Theory of Interest. 3rd ed. New York: McGraw-Hill; 2009. Chapter 3 (amortization schedules).
What can make this go out of date
- none at runtime; Census Rental Housing Finance Survey (2021 vintage) and Fannie Mae eligibility matrix quoted in prose
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