Every listing says it's a great deal. Check the math.
Put in the price and rent. Get your real monthly cash flow, what happens if your assumptions turn out wrong, and the most you should offer, with every step shown. We fill in typical numbers for what you don't know.
Built by first-time buyers who wanted a calculator that explains itself. Free, no account needed. Your numbers stay in your browser. Kept free by coffees from people it helped.
Turnkey duplex, fully let
For sale
- Asking price
- $255,000
- Offer $203,500 or less to meet your goals: net yield 1 pt above your loan rate, break-even cash flow, 1.25 DSCR
- Seller's yield claim
- “10.1% rental yield!”
- That's gross. After costs it's 5.6%, and only -0.0% on the cash you put in
- Seller's cash flow claim
- “Cash flow from day one!”
- −$2/mo. A tougher year (rent 10% down, one more empty month, costs up, one big repair): −$756/mo
Three questions to answer before you sign anything
Same duplex as above, with typical costs filled in. Every figure on this page comes from the analyzer itself.
What will I actually keep?
Each month, with typical costs filled in
- Rent
- $2,140
- Empty months, averaged out
- −$178
- Mortgage
- −$1,229
- Tax, insurance, repairs and management
- −$735
- You keep
- −$2/mo
How much can go wrong?
- Your assumptions
- −$2/mo
- A tougher yearRent 10% down, one more empty month, running costs up, one big repair
- −$756/mo
- Cash flow hits zero at 1.0 empty months a year, or a loan rate of 6.0%, or rent -0% lower.
What should I offer?
Asking
$255,000
Most you should offer
$203,500
The most you should offer, so that:
- net yield 1 pt above your loan rate
- Pays for itself (cash flow $0 or more)
- 1.25× DSCR
You can also save deals, compare them side by side and export a PDF report to share.
Why we built it
We wanted to buy our first investment property and had no idea what we were doing. Agents, sellers, everyone threw numbers and jargon at us, and nudged us to just sign.
We didn't want to be told it was a good deal. We wanted to understand the numbers ourselves. The calculators we found were black boxes, so we made one that explains itself.
It's free, with no ads and no paywall, and we don't sell your data. Hosting and new features come out of our own pockets. If it helped you, a coffee goes a long way.
The people who built this
Buy us a coffeeLearn the numbers
Plain-English guides to everything we wish someone had explained to us.
- What Is Cap Rate? Formula, Calculator & ExamplesCap rate = NOI ÷ price. Use the free cap rate calculator, follow a worked $240k example, and learn why seller cap rates run 1–2 points too high.Calculators
- Cash-on-Cash Return: Calculator, Formula & BenchmarksCalculate cash-on-cash return for free, see a worked example at a 7% mortgage rate, and learn what a good CoC return is in 2026.Calculators
- How to Analyze a Rental Property (Step-by-Step)A complete walkthrough of rental property analysis: income, expenses, financing, and all the key metrics—ROI, cap rate, cash flow, and IRR—so you can make a confident buy or pass decision.How-To Guides
- DSCR Calculator: Debt Service Coverage for RentalsFree DSCR calculator for rental properties. Learn both DSCR formulas lenders use, what a good DSCR is, and how to raise one that falls short of 1.25.Calculators
Questions we had too
Is it really free?
Yes. Every feature — ROI, cash flow, IRR, what-if tests, the Deal Negotiator, PDF export, and saved deals — is completely free. No credit card, no subscription, no trial that runs out.
Who built this, and why is it free?
A few of us who wanted to buy our first investment property and knew nothing. Everyone pushed numbers and jargon at us, and the calculators we found were black boxes. So we built the one we wished we had. We keep it running ourselves, and some of the people it helps buy us a coffee. If it saved you time or money, you can do the same — if not, no hard feelings.
Do I need to sign up to analyze a deal?
No. The analyzer works with zero friction — no email, no card. You only need an account if you want to save deals across sessions.
Are my numbers stored anywhere?
When you're not signed in, your inputs stay in your browser. We don't send them anywhere. If you sign in and save a deal, only the deals you explicitly save are stored in your account.
How accurate are the calculations?
Every metric (cap rate, cash-on-cash, IRR, NOI, DSCR) uses the standard industry formulas, and we show the full step-by-step computation behind each one — no black boxes. Compare it to your spreadsheet and you'll see the same numbers. For what you don't know yet (closing costs, vacancy, running costs, growth) we fill in typical numbers, mark them clearly, and link to how to find yours. The price, rent and interest rate are always yours to enter.
How is this different from a spreadsheet or a Zillow estimate?
Spreadsheets hide assumptions and don't test what happens if your assumptions are wrong. Listing sites skip vacancy, repairs, and rate changes. The analyzer fills in typical costs, shows how much can go wrong, runs a year-by-year forecast, and tells you the highest price that meets your goals.
Does the analyzer work for properties outside the US?
Yes — it works for any country. Every metric (cash flow, cap rate, IRR, the bad-year check, the Deal Negotiator) is pure math and needs no location data.
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