About PropCalc

PropCalc is a small, focused set of ten real estate calculators: Cash on Cash, Rental ROI, Rent vs Buy, Mortgage, Fix & Flip, Affordability, Cap Rate, 70% Rule, DSCR, and BRRRR. Each one takes the numbers you enter and runs them through a standard formula, then shows you the result immediately. There is no account to create and nothing to install — you land on a calculator page, change the inputs, and the results update as you type.

Who PropCalc Is For

The calculators are built for the same audience that types "cash on cash return calculator" or "rent vs buy calculator" into a search engine: rental property investors sizing up a deal, house flippers checking whether a project's numbers work, first-time buyers comparing renting against buying, homeowners deciding whether an extra mortgage payment is worth it, and anyone trying to work out how much home they can reasonably afford. If you already have a spreadsheet that does this, PropCalc is a faster way to sanity-check the same math without building the sheet yourself.

How the Calculators Work: Client-Side, Nothing Sent to a Server

Every calculation runs as JavaScript in your own browser tab. When you type a number into an input field, the site reads that value, plugs it into a formula, and writes the result back to the page — all without a network request. PropCalc has no login system, no database of user submissions, and no server-side code that processes your figures. Your income, purchase price, loan terms, or rent numbers never leave your device. You can confirm this yourself: open your browser's network tab while using any calculator and you'll see no requests firing as you change the inputs.

What the Formulas Are Based On

The math behind each calculator is standard, published real estate and lending arithmetic — the same formulas you'd find in a finance textbook or a lender's underwriting guide: the amortization formula for a fixed-rate loan payment, net operating income and cap rate for evaluating a rental's unleveraged return, cash-on-cash return for the return on the cash actually invested, and debt-to-income ratios for estimating how much home a given income can support. Nothing here is a proprietary model or a machine-learning prediction — every output can be reproduced by hand with the same inputs and the formula shown on each calculator's page.

The Limits of These Tools

Each calculator only knows what you tell it. It cannot account for factors you don't enter — a market's specific vacancy trends, a lender's exact underwriting overlays, unexpected repair costs, tax law changes, or how a specific ARM might reset. The rent-vs-buy and mortgage calculators assume a fixed rate for the full term you enter; the fix-and-flip and rental calculators assume the appreciation, rent growth, and expense percentages you provide hold steady, which real markets rarely do exactly. Treat every result as an estimate built from the assumptions you supplied, not a guarantee of what will actually happen with a specific property or loan. PropCalc is an educational tool, not financial, tax, or legal advice — for a decision involving real money, run the numbers here as a starting point and then talk to a qualified professional who can look at your specific situation.

Free to Use, Supported by Ads

PropCalc is free, with no sign-up and no paywall. The site is designed to be supported by advertising rather than subscriptions, but advertising is not active here yet, so you won't see any ad placements alongside the calculators today.