Buying typically wins on long horizons (10+ years) when you can put enough down to avoid PMI, your DTI is well under 43%, and the local price-to-rent ratio is under ~18. Renting wins when rates are high, you'd be stretched on monthly cost, you might move within 5 years, or the price-to-rent ratio is over 22. This tool runs the full scenario both ways and picks the better one.

At minimum, cover the down payment + closing costs + a 3-month emergency fund. The tool calls that out as 'cash to close + emergency fund target'. Buying with the bare minimum and zero reserve is the fastest path to being house-poor, the engine deliberately recommends 'save and buy' when reserves are short.

Lenders cap conventional loans at a back-end DTI (all monthly debt + housing / gross monthly income) of 43%. FHA goes a bit higher. The tool flags anything above 43% as a hard cap and warns when you're over 36% (the 'comfortable' threshold). Front-end DTI (just housing / income) is typically 28–31% for comfort.

Qualifying = the lender will give you the loan. Being ready = you can cover the down payment, closing, monthly carrying cost, AND keep a reserve for repairs, vacancies, and life. The tool models all four. You can pass the lender check and still get a 'save and buy' recommendation because of reserves.

Median home price ÷ (median rent × 12). Under 15 strongly favors buying; 15–20 is mixed; over 22 favors renting. It's the housing market's version of a P/E ratio, high price-to-rent means you're paying a steep premium for ownership relative to renting the same square footage.

Counted as net worth but NOT liquid for the down payment. Pulling from a 401k for a home usually nets ~70¢ on the dollar after early-withdrawal penalty + tax. Brokerage and sale proceeds from an existing home are treated as liquid.

Cash paid at closing to lower your interest rate. Each point costs 1% of the loan amount and typically reduces the rate by ~0.25%. They're worth it only if you'll keep the loan past the break-even point (usually 4–6 years). The Tune drawer's Rate + Points section lets you model 0–4 points and see the trade-off live.