Home and mortgage calculator
Home Affordability Calculator
This calculator estimates the maximum home purchase price supported by the income, debts, down payment, housing costs and mortgage assumptions you enter. It is an educational borrowing-capacity estimate, not lender approval or an assessment of whether the resulting payment fits your household budget.
How this estimate works
The calculator works backward from the qualification limits used in the calculation. It determines how much room remains for a mortgage payment after property taxes, heating costs and the applicable portion of condominium fees are considered, then converts that payment capacity into an estimated mortgage and purchase price. When mortgage insurance applies, the estimated financeable premium is included in the mortgage used for qualification.
Key calculation assumptions
The estimate uses the qualifying rate and debt-service limits shown in the calculator. Income and property taxes are annual inputs; heating, condominium fees and other debt payments are monthly. The debt-service calculation uses 50% of condominium fees. Property taxes, heating costs and condominium fees remain fixed at the amounts you enter while the calculator solves for the maximum purchase price.
Supported scope
This calculator is designed for owner-occupied purchases with one or two residential units and a non-borrowed down payment. It models supported insured and uninsured purchase scenarios under the assumptions described in the Mortgage Qualification Rules reference.
Detailed rules
For the qualifying-rate test, GDS and TDS definitions, minimum down-payment rules, mortgage-insurance premiums, longer insured amortizations and full worked examples, see the Mortgage Qualification Rules reference.
Example
Suppose a household has gross annual income of $120,000, a $100,000 down payment, a 5.00% mortgage-rate assumption, a 25-year amortization, annual property taxes of $4,800, monthly heating costs of $150, no condominium fees and $600 of other monthly debt payments.
Under the assumptions used by the calculator, the estimated maximum purchase price is approximately $551,372. The base mortgage is approximately $451,372 and the estimated mortgage-insurance premium is approximately $12,638, producing a mortgage used for qualification of approximately $464,010. The qualifying payment is approximately $3,250 per month. GDS is approximately 38.00% and TDS is 44.00%, so TDS is the limiting constraint in this example.
Limitations
This calculator does not reproduce a lender’s complete underwriting process. It does not assess creditworthiness, verify income or debts, determine mortgage-insurance or property eligibility, or estimate all closing costs. Mortgage rules, insurer requirements and lender practices can change or differ from the assumptions used here. The result is an educational estimate and may contain errors or omissions.
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Related References
The shared reference explains the stress test, GDS/TDS, minimum down payments, insurance premiums, longer amortizations and the complete calculation examples.