About RealPropTools

Most free real estate calculators are wrong in ways their users cannot see — a misplaced decimal, an unstated day-count convention, a coverage ratio that reports a pass on the very deals it should be flagging. RealPropTools builds the same tools to institutional underwriting standards and documents every assumption, so the arithmetic can be audited rather than trusted.

Mission and vision

Our mission is to put institutional-grade debt sizing and commercial real estate underwriting in the hands of the people who need it before a lender does: investors weighing an acquisition, brokers pricing a listing against the financing a buyer can actually raise, and analysts who need a second, independent set of numbers to check a model against.

The gap we are closing is a specific one. A lender sizes a commercial loan against several constraints at once and advances whichever is smallest, but most free tools model only one of them. The result is a calculator that tells a borrower the deal works at seventy percent leverage when the income will only support sixty-five — a shortfall that surfaces at the closing table rather than at the kitchen table. Our vision is a suite where every figure is the figure a credit committee would arrive at, shown with the working that produced it.

Calculation standards

Every calculator on the site runs on one shared, unit-tested math core. No tool carries its own copy of a formula, so a correction made once reaches every page that depends on it. The core measures are defined the way lenders and investment committees define them:

• Debt service coverage ratio (DSCR) — net operating income divided by annual debt service. It answers whether the property's income pays its mortgage, and by what margin.
• Debt yield — net operating income divided by the loan amount. It ignores rate and amortization entirely, which is why lenders lean on it when a generous appraisal or a low rate makes the other tests look comfortable.
• Capitalization rate — net operating income divided by price or value. It describes the property unleveraged, independent of how any buyer finances it.
• Loan-to-value (LTV) — the loan as a share of the lesser of purchase price and appraised value. Its complement is the equity the buyer has to bring.
• Cash-on-cash return — annual cash flow after debt service divided by the total cash invested, meaning the down payment plus closing costs rather than the down payment alone.

Where these interact, the tools apply them together. A commercial loan is sized as the lesser of the amount value supports and the amount income supports at the required coverage, and the tools report which constraint bound. Day-count conventions — 30/360, Actual/360 and Actual/365 — are named on the page that uses them, because the same quoted rate costs a borrower more under one than another. Solvers that cannot reach an answer return a stated reason rather than a number they cannot justify. The full approach, including how rounding is handled and what each solver does at the edge of its range, is set out on the methodology page.

Who the tools are for

Investors use the suite before they commit to a price: to see what net operating income a property actually produces once vacancy, reserves and management are counted, what loan that income supports at today's rates, and whether the leverage on offer adds to their return or subtracts from it. Brokers use it to price a listing against the financing a buyer can realistically raise, and to explain to a seller why a lender's view of the income differs from the marketing package. Analysts use it as an independent check — a second set of numbers, built from the same definitions a credit committee uses, to test a model against before it goes in front of anyone else.

Who builds these

RealPropTools is built and maintained by commercial real estate finance professionals. The working background behind the tools is commercial mortgage underwriting and income-property acquisition analysis: sizing debt against loan-to-value and debt service coverage constraints, building and defending net operating income statements, and stress-testing valuations against the cap rate movements that decide whether a deal survives its hold period.

That background sets the standard the site is held to. Every calculator and the underwriting guide that accompanies it is written, tested and reviewed in house before it ships. The emphasis is on work that can be checked figure by figure: every convention is stated on the page that uses it, and every result can be reproduced from the inputs shown beside it.

Privacy and corrections

Nothing you enter is transmitted anywhere: every figure is computed in your browser, and the tools have no accounts and store no inputs. If a result here disagrees with yours, we want to know — the contact page explains what to send so the discrepancy can be reproduced, and confirmed errors are corrected in the shared core so the fix reaches every tool at once.

Note: Calculations are provided for informational and planning purposes only and do not constitute formal appraisal, legal, tax, or financial advice.