About RealEstateCalculations.net

RealEstateCalculations.net is a collection of focused real-estate investing calculators — rental property cash flow, cap rate, cash-on-cash return, rent vs. buy, fix-and-flip, and the 1% rule — that run entirely in your browser. It is published by Sumvia, the team behind the Sumvia.net calculator network.

Standard math, shown openly

Every calculator here uses the standard industry formulas — NOI and cap rate, levered cash-on-cash return, amortized loan payments, the 70% flip rule — with the conventions stated plainly (operating expenses exclude the mortgage; cash invested means the cash that actually left your pocket). Each page names what it calculates and shows a worked example, so you never have to wonder where a number came from.

Browser-native, no accounts

Nothing you enter — prices, rents, loan terms — is transmitted, logged, or stored. All calculation happens on your device, there is no registration, and the tools stay usable on a flaky connection once the page has loaded. This is a deliberate design constraint of every Sumvia site.

Tested calculation logic

The real-estate engine is implemented as small, typed functions with automated tests checked against known reference figures (for example, a $220,000 rental at 20% down and $2,200 rent producing a 7.85% cap rate and 6.21% cash-on-cash return). The worked examples in page copy are generated by the same code that powers the calculators, so the documentation cannot drift from the implementation. See the methodology and accuracy page for the full approach.

Not financial advice

These calculators provide general educational estimates. They cannot account for local market conditions, taxes, financing structures, or the condition of a specific property, and they are not a substitute for due diligence or professional guidance. Verify any consequential figure with qualified professionals before relying on it.

Get in touch

Found a problem, or want to suggest a calculator? See the contact page — reports of suspected calculation issues are especially welcome and are treated seriously.