Real Estate ROI Calculator

A single-file calculator for rental property numbers. Enter the purchase price, down payment, monthly rent, vacancy rate and monthly expenses (mortgage, tax, insurance, maintenance) and see monthly cash flow, annual cash flow, cash-on-cash return, cap rate and break-even rent — updated live as you type. No backend, no account, nothing is uploaded anywhere — everything runs on the buyer's own computer, offline, in any modern browser. Default numbers are clearly marked SAMPLE and must be replaced with the buyer's own figures. This is a simple arithmetic aid, not financial advice.

What's inside: index.html (the whole tool), README.md, cover.png.

License: Use this tool for your own business. Do not resell or redistribute the file.