You found the listing. The Saturday showing is two hours away. You’re already mentally arranging furniture in the living room.
Stop. Open a tab. Run this 5-minute affordability check first.
The point isn’t to talk yourself out of buying. It’s to walk into the showing knowing whether the asking price is within your budget, not just within what a lender said you “qualify for.” Those two numbers are not the same — and in 2026, they can be wildly apart. (If you’re still on the bigger question of whether to buy at all this year, our framework on whether you should buy a house in 2026 is the post that comes before this one.)
Here’s the move.
The 5 Numbers to Pull Up
You need five things on screen: the listing price, your gross monthly income, your current monthly debt payments, your liquid savings, and the property tax rate for the zip code (one search). That’s it.
Run these checks in order. If any of them lights up red, the listing is a stretch — not a “no,” but a “go in with your eyes open.”
| Check | What to calculate | Green light | Red light |
|---|---|---|---|
| 1. All-in monthly payment (PITI + HOA) | Principal & interest + property tax/12 + homeowners insurance/12 + HOA | ≤ 28% of gross monthly income | ≥ 32% of gross monthly income |
| 2. Total debt-to-income | All-in housing payment + every other monthly debt (auto, student loans, credit-card minimums) | ≤ 36% of gross monthly income | ≥ 43% of gross monthly income |
| 3. Cash-to-close reality | Down payment + closing costs (≈ 3% of price) + escrow setup + moving + 1% of price for immediate repairs | Covered by liquid savings (not retirement, not gifts you haven’t confirmed) | You’re tapping a 401(k) or asking family |
| 4. Emergency reserve after closing | Liquid savings remaining after cash-to-close ÷ new monthly all-in housing spend | ≥ 3 months of housing-and-essentials covered | < 1 month — house-rich and cash-poor on Day 1 |
| 5. Property-specific gotchas | HOA fee, special-assessment history, age of roof/HVAC/water heater, flood zone, septic vs sewer, well vs municipal water | All known and budgeted | Any one of these unanswered before the offer |
Five rows. About four minutes if you’ve done it before, six the first time.
Why Each Number Actually Matters
Check 1 and 2 — the 28/36 rule — is the conservative end of mortgage lending math. Most explainers, including Bankrate’s breakdown of the 28/36 rule, describe it as a general guideline: no more than 28% of gross monthly income on housing (PITI plus HOA), no more than 36% on total debt. Lenders will absolutely approve you well above those numbers — the Fannie Mae Selling Guide on debt-to-income ratios allows manually underwritten conventional loans up to 45% total DTI with compensating factors, and casefiles run through Desktop Underwriter can reach 50%. Approval is not the same as affordability. The 28/36 thresholds are designed to absorb a furnace replacement, a job change, or a property-tax reassessment without forcing a hard choice.
Check 3 — closing costs — is the number nobody mentions during the listing photos. Closing costs typically run 2% to 5% of the loan amount, and the Bankrate 2025 state-by-state average closing costs analysis (using Lodestar data) shows real geographic spread — from around $1,500 in the cheapest states to over $17,000 in the District of Columbia. On a $400,000 home, that range alone is an $8,000–$20,000 swing. Budget the higher end of your state’s average, not the lower.
Check 4 — the post-close emergency reserve — is the one most buyers skip. Wiping out your savings to close means the first water-heater failure or HVAC repair becomes a credit-card event. A home that empties your buffer isn’t “affordable” — it’s a single emergency away from financial stress. Three months is the floor, six is comfortable.
The 5-Minute Rule
If you can’t run this exercise in five minutes for any listing you’re seriously considering, the math isn’t the bottleneck — your tracking is.
That’s why many house hunters end up building a spreadsheet after a few showings. You’re trying to remember whether 2912 Maple had a $300/month HOA, or whether that was the place on Birch with the special-assessment history. The House Search Tool pre-builds the 5-minute affordability check across every listing you tour, so you can rank them apples-to-apples instead of by which one had the cleanest staging.
For the buy/don’t-buy decision once the math passes and you’re choosing between two finalists, the House Buying Decision Helper is built specifically for that head-to-head call.
And if you want to model paying it off faster the moment you sign, the Mortgage Payoff Calculator shows what each extra principal payment is actually worth over the life of the loan.
The Move, One More Time
Before any Saturday showing:
- Pull up the five inputs (income, monthly debts, savings, listing price, tax rate).
- Run the 5-check table above.
- Anything red? Bring it up with the agent and the lender before you fall in love at the front door.
Five minutes. That’s the whole post.
Disclaimer: This post is for informational and educational purposes only and does not constitute financial, tax, mortgage, or legal advice. Qualifying ratios, closing costs, loan products, and tax treatment vary by state, lender, and your individual situation — consult a licensed mortgage advisor, CPA, or financial planner before making decisions based on this content.
