A mortgage affordability calculator, not a yes from a bank
“How much house can I afford?” is two questions. The first is what payment a guideline debt-to-income ratio will support. The second is whether that payment still leaves room for food, childcare, maintenance, and a reserve. HouseAfford answers the first with a transparent formula. You still have to answer the second.
The tool solves for the largest purchase price whose monthly housing cost — principal, interest, property tax, insurance, HOA, and an optional PMI/MIP estimate — fits inside both the front-end and back-end caps you choose.
Front-end DTI
Housing payment ÷ gross monthly income. Conventional education tables often use 28%. FHA tables often use 29%.
Back-end DTI
Housing plus other debts ÷ gross monthly income. Conventional 36%. FHA 41%. This cap binds when car loans and cards are heavy.
What to enter
- Gross income — annual salary or monthly pay before tax. Overtime and bonus only if a lender is likely to count them.
- Monthly debts — minimums on installment and revolving accounts, plus court-ordered payments. Utilities and groceries do not belong here.
- Down payment — dollars you will bring, or a percent of price. Under 20% usually means mortgage insurance.
- Rate and term — the note rate you can actually get, not last year’s average.
- Tax, insurance, HOA — these scale with price in most markets. A cheap principal payment can still fail if the mill rate is high.
Read the result the way a loan officer would
The headline number is maximum home price. Under it is maximum loan. If the front-end pill is highlighted, housing itself is the limit. If the back-end pill is highlighted, other debts are crowding out the mortgage. If debts already exceed the back-end cap, no purchase payment fits until those balances fall.
Automated underwriting (Desktop Underwriter, Loan Product Advisor, TOTAL Scorecard) can approve higher ratios when credit, reserves, and residual income are strong. Treat 28/36 and 29/41 as published consumer guidelines, not a ceiling carved in statute.
Affordability is more than DTI
Closing costs often run 2%–5% of price. Homes need maintenance. A payment that qualifies can still be a bad month. If you want a payment you can live with — not just one a guideline will print — start with the calculator, then read affordability tips and the DTI explainer.
HouseAfford is an educational estimate, not a pre-approval, pre-qualification, or offer to lend. Lenders also weigh credit, assets, employment, property type, and automated underwriting. Actual approval and payment will differ.