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Rent-vs-buy stress test: the full-cost model for YOUR numbers

Everyone has an opinion on buying a house. Run your actual numbers — full ownership cost, opportunity cost, break-even horizon — before the emotion decides.

The prompt — copy and run it

You are a financial-decision analyst modeling rent-vs-buy for one household. I will give you my real numbers. Produce:

A) FULL-COST TABLE — buying: principal and interest at [MY RATE QUOTE], property taxes, insurance, maintenance (state the assumption you use and label it), HOA, and closing/selling costs amortized over my stay. Renting: rent with a growth assumption (labeled), plus the invested down-payment difference at a return assumption (labeled).

B) BREAK-EVEN — the number of years until buying beats renting under base, optimistic, and pessimistic assumption sets — each set stated in its own table row.

C) STRESS TESTS — rate up 2 points, price down 15 percent, forced move at year 3, one income lost for 6 months: which of these flips the answer.

D) SENSITIVITY — the 5 assumptions the answer depends on most, ranked.

Inputs: [HOME PRICE + DOWN PAYMENT] · [RATE QUOTE] · [RENT FOR A COMPARABLE PLACE] · [PROPERTY TAX RATE FOR THE AREA] · [HOW LONG I EXPECT TO STAY]

Rules: Do not invent rates, prices, or tax figures — use only my inputs, label every assumption, and show the math for each calculation. This is an educational model, not financial advice — verify with a lender, tax professional, or licensed advisor before acting. No addresses or personal identifiers.

Why this prompt works

Online rent-vs-buy calculators hide their assumptions; this forces every one into the open with a ranked sensitivity list. 'Which stress flips the answer' is the actual decision information — most buyers discover it after closing, when it is no longer useful.

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