DealMath: Rental Property Calculator

Cap rate, cash-on-cash, deal grade and max offer on any listing, auto-filled from the page. Save, compare, BRRRR and print.

DealMath tells you if a rental property makes money, right on the listing page. Open a home on Zillow, Redfin, or Realtor.com and a calculator appears in the corner, already filled in with the price, property taxes, and HOA from the page. Add the rent you expect and get your numbers instantly, with a grade against your own targets. FREE Monthly cash flow, cash-on-cash return, and cap rate Mortgage payment, NOI, cash needed, DSCR, the 1% rule, gross rent multiplier, and break-even occupancy Deal grade (A to F) based on targets you set for cash flow, cash-on-cash, cap rate, and DSCR Green fields are read from the page, dashed fields are estimates, and every field is editable Your rate, down payment, and expense assumptions are remembered between listings Save up to 3 deals, with notes and a status (Watching, Visiting, Offered, Passed) PRO ($9/month, or save with the annual plan) Max offer price: set a goal and see the highest price that hits it BRRRR mode: rehab, refinance, cash left in the deal, and cash recovered Projections: equity, total return, and cash flow over time House-hack and multi-unit mode: add rents per unit and remove the unit you live in More loan types: FHA, seller financing, and interest-only, plus points Rent memory: reuse the rent you typed for a ZIP code and bedroom count Price change tracking: see how much a saved listing's price has moved One-page print summary of any deal Unlimited saved deals, side-by-side comparison ranked by cash-on-cash, CSV export, and rate and rent stress tests PRIVACY No account, no ads, no tracking. Your saved deals and settings stay in your browser. The extension only contacts Gumroad to check a Pro license key. Full policy: swensondigital.carrd.co DealMath is not affiliated with Zillow, Redfin, or Realtor.com. Results are estimates, not financial advice. Verify taxes, insurance, and rent before making an offer.