Mortgage affordability determines the maximum home price you can reasonably purchase based on your income, existing debts, down payment, interest rate, and loan term. Lenders use standardized debt-to-income (DTI) ratios to evaluate whether a borrower can comfortably manage monthly mortgage payments alongside their other financial obligations.

Understanding your affordability range before house-hunting helps you set realistic expectations and focus your search on properties within your budget. It also strengthens your position when making offers, as sellers and agents take pre-qualified buyers more seriously.

The 28/36 rule is the industry-standard guideline that most lenders follow when evaluating mortgage applications. The front-end ratio (28%) limits your total housing expenses -- including mortgage principal, interest, property taxes, and insurance -- to no more than 28% of your gross monthly income.

The back-end ratio (36%) caps your total monthly debt payments at 36% of gross income. This includes your housing costs plus all other recurring debts like car loans, student loans, credit card minimums, and child support. Some lenders may allow higher ratios for borrowers with excellent credit scores or significant assets.

Several key factors influence how much home you can afford. Your annual income is the primary driver, but interest rates play an equally critical role -- even a 1% rate increase can reduce your purchasing power by tens of thousands of dollars. The down payment percentage directly impacts your loan amount; a larger down payment means a smaller mortgage and lower monthly payments.

Existing debt obligations reduce the amount available for housing costs. Car payments, student loans, and credit card balances all count against your back-end DTI ratio. The loan term also matters: a 15-year mortgage has higher monthly payments than a 30-year term but saves significantly on total interest paid over the life of the loan.

This calculator estimates your maximum affordable home price based on the 28/36 rule, but your actual affordability may differ. Additional costs like property taxes, homeowner's insurance, HOA fees, private mortgage insurance (PMI), and maintenance are not fully captured in this calculation and can significantly impact your true monthly housing costs.

Financial advisors often recommend buying below your maximum affordability to maintain a comfortable financial cushion. Unexpected expenses, job changes, and market fluctuations are all realities of homeownership. A good rule of thumb is to keep your total housing costs to 25% or less of your take-home pay, leaving room for savings, investments, and lifestyle expenses.