RentHack shows you exactly how rental income offsets your mortgage — step by step — so you know if a 2–4 unit property actually works before you make an offer.
Free duplex, triplex & fourplex deal analyzer — built for house hackers and first-time multifamily buyers.
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Every other tool assumes you know what cap rate means. RentHack explains every number as you enter it — so you learn while you analyze.
No blank spreadsheet staring back at you. We ask the right questions in the right order.
Hover over any metric and we'll tell you exactly what it means and why it matters.
Effective mortgage cost, average equity growth, and cash flow — the three numbers every house hacker needs.
Invite a co-buyer, spouse, or agent to view and collaborate on your analysis in real time.
📍 123 Maple St — 2-unit
Your monthly housing cost after rent
"I ran 8 deals in a weekend before making an offer. The effective mortgage number made it so clear which properties actually worked for my situation."
"I'm not a numbers person at all. The fact that it explains every term as you go made this the only tool I could actually use without a spreadsheet course first."
"The break-even vacancy rate is something I'd never even thought about. Now it's the first thing I look at. Absolute game-changer for a duplex buyer."
Add the asking price, down payment, and loan terms — whether you're analyzing a duplex, triplex, or fourplex. We fill in smart defaults so you're never staring at a blank field.
Enter the rent for each unit, plus estimated costs like insurance, taxes, and maintenance. We'll flag anything that looks unusual.
Your effective monthly mortgage cost, cash flow, cap rate, DSCR, and break-even vacancy rate — all in one clean summary you can share with your partner or agent.
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Not at all. RentHack is designed specifically for first-time buyers who are considering a 2–4 unit property. Every term is explained in plain English as you go.
RentHack is purpose-built for 2–4 unit residential properties — duplexes, triplexes, and fourplexes — which are the most common house hack properties.
Your effective mortgage is your actual monthly housing cost after the rental income from your tenants is subtracted from your mortgage payment. It's the number that tells you: what will I actually pay to live here?
Yes — the free plan lets you run a full analysis with no credit card required. You only need to upgrade if you want to save multiple deals or export a PDF report.
Yes. All data is stored in Supabase with row-level security — only you can see your deals. We never sell your data and you can delete your account at any time.
Duplex cash flow = gross rental income − vacancy loss − operating expenses (taxes, insurance, maintenance, CapEx, management) − debt service (mortgage P&I). RentHack walks you through each input and calculates this automatically — including a 10-year projection and your break-even vacancy rate.
Most lenders want a Debt Service Coverage Ratio (DSCR) of at least 1.25 — meaning the property's net operating income covers the mortgage payment by 25%. A DSCR below 1.0 means the property doesn't generate enough income to cover debt service. RentHack calculates your DSCR automatically as you enter your numbers.
A house hack means you live in one unit of a 2–4 unit property and rent out the others — giving you access to owner-occupied financing (lower down payments, better rates) while your tenants offset your housing costs. RentHack is purpose-built for this: it models owner-occupied cash flow separately from investor-only returns, so you see your actual effective monthly housing cost.
Free to use. Takes 10 minutes. No spreadsheets required.
Analyze your first deal →Free duplex & multifamily deal analyzer — no experience required
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