Know if it cash flows before you make an offer. The same underwriting framework I've used on commercial deals for 22 years — not just for agents, for anyone about to make this decision.
This is the actual tool, not a mockup — the same math, running live below.
Enter a listing price, down payment, and rent. Results calculate live as you type.
From the "How to Buy a Duplex" video series
Most property calculators just spit out a number. This one shows you why — the same line items a lender or appraiser will actually check, so you're not walking into an offer on a guess.
Free. Listing price, down payment, rent. Know in 10 seconds if it's worth a closer look.
Acquisition costs, debt service, NOI, cap rate, cash-on-cash. The same underwriting a lender will do, before you make an offer.
One clear answer: what it costs you to live there, or what it pays you as a rental. No spreadsheet jargon, no guessing.
What separates a good decision from a lucky guess is knowing the numbers before you make the offer.
A real example from the full Property Analysis tab
Whether you're screening your fifth deal or looking at your first duplex, the question is the same: does this actually cash flow? Here's how the tool works either way.
The tool shows your real monthly cost after rent covers part of the mortgage — what it actually costs you to live there.
The easiest way to start the move from labor to capital: your first deal, living in it while it works for you.
The tool shows monthly and annual cash flow, cap rate, and cash-on-cash return — the numbers that tell you if it's a deal or a mistake.
The same screen, run the same way, whether this is your first deal or your fifth.
Five tabs. Zero fluff. Built for real deals — the first one's free.
Secure checkout via Stripe. You'll be redirected to your download immediately after purchase.
Hi, I'm Arthur DeJohn. 20+ years in commercial real estate, underwriting income properties for investors and brokers.
I built this because most first-time buyers run the numbers on a property the same way they'd guess a tip — and the ones who don't have a framework are the ones who find out they overpaid after closing, not before.
This is the same framework I've used with real clients for two decades, packaged so you can run it yourself in under 5 minutes.
Use it once. See what it tells you about your next deal.
No. Every input has a tooltip explaining what to enter. The How-to-Use tab walks you through it in plain English. If you can fill in an Excel cell, you can use this.
Excel (2013 or newer), Excel 365, Google Sheets, or Mac Numbers. Standard .xlsx format.
Free templates skip vacancy allowance, reserves, and the acquisition costs that actually change whether a deal cash flows. This one doesn't.
Thinking about a 5+ unit building or a value-add deal? I'll underwrite it directly — starting at $500 per property. Contact me at adejohn@adjcommercial.com after purchase.
The question isn't whether you'll find a listing. It's whether you'll know if it's actually a good one when you do.
Get the Tool — $47Instant download • 7-day guarantee • Yours forever