US Mortgage Affordability Calculator

How this calculator works

The housing budget is the smaller of your housing-ratio limit and the amount left under your total-debt limit after existing payments. The model solves for a home price whose financed principal, estimated property tax, insurance, HOA and entered PMI fit that budget. Property tax uses your chosen percentage of purchase price, which may differ from an assessed-tax bill. The DTI limits are scenario inputs, not universal lending requirements.

Formula and rules

Housing budget = max(0, min(monthly gross income × housing DTI, monthly gross income × total DTI − existing debts)). Home price is solved from mortgage payment + price-based property tax + insurance + HOA + entered PMI = budget.

Assumptions and limitations

Fixed-rate monthly amortisation; property tax proportional to purchase price; PMI supplied by you rather than inferred. No closing costs, tax deductions, maintenance, future rate changes, credit underwriting or lender approval. A budget too small for the model shows no financed-purchase estimate.

Worked example

For $120,000 annual income, a chosen 30% housing ratio and 40% total ratio with $500 existing monthly debt, the housing ceiling is $3,000 a month. With no tax or insurance, a $60,000 down payment and 0% over 30 years, that supports $1,080,000 principal and a $1,140,000 modelled price.

Estimated home-price ceiling under your limits

$1,140,000.00

Mortgage principal

$1,080,000.00

Monthly principal and interest

$3,000.00

Monthly total housing cost

$3,000.00

Official sources and review

Reviewed against the sources below on 2026-10-06. Rates are held in versioned rule modules. Versioned rules, official source review and year-specific calculation tests.

• CFPB: Debt-to-income ratio ↗

  DTI compares monthly debt payments with gross monthly income; lending requirements vary.

Common questions