House Affordability Calculator
Estimate an affordable home price from income, monthly debts, down payment, mortgage rate, taxes, insurance, HOA and front/back debt-to-income limits.
- Uses both front-end and back-end DTI limits
- Includes property tax, insurance and HOA
- Solves the mortgage amount rather than guessing a price
Calculator workspace
Change any assumption and recalculate. Your entries stay in this browser unless you choose to share or copy a result.
What this House Affordability Calculator calculates
A home-price estimate is only useful when it is tied back to the monthly payment a household can realistically support. This calculator starts with gross monthly income, applies both a front-end housing ratio and a back-end total-debt ratio, and uses the tighter limit. It then subtracts insurance and HOA and solves for a mortgage amount while also allowing property tax to rise with the calculated home price. That is more realistic than taking a monthly payment cap and dividing it by a mortgage factor alone.
The result is intentionally more than a single number. Supporting figures are shown beside the headline answer so you can see which part of the calculation is driving the outcome. This makes the tool useful for scenario testing: change one assumption, calculate again, and compare the supporting values rather than relying on a black-box result.
Formula and calculation method
Housing limit = min(income × front DTI, income × back DTI − other debts), then solve the mortgage that fits principal/interest + tax + insurance + HOA.
Inputs are validated before calculation and the arithmetic runs locally in the browser. Monetary fields use the selected currency only for display formatting. The calculator does not retrieve bank, payroll, property, medical, market or exchange-rate data from an external service.
How to use it
- Enter values that describe the same scenario and reporting period.
- Keep percentages and units consistent with the labels shown beside each input.
- Select Calculate and review both the headline result and the supporting metrics.
- Change one assumption at a time to understand sensitivity instead of accepting a single scenario.
- Use Copy Result, Share Result or Save Result Image when you need to keep a record of the calculation.
Worked example
Suppose a household earns 120,000 per year, has 650 of other monthly debt, can put 50,000 down, and is considering a 30-year mortgage at 6.5%. With a 1.2% annual property-tax assumption, 180 monthly insurance, and 28%/36% DTI limits, the result shows the purchase price supported by the stricter debt-ratio test. Change the down payment or interest rate to see immediately how affordability moves.
How to interpret the result
Treat the result as a planning ceiling, not as a lender approval. Actual underwriting can include credit score, documented income, reserves, mortgage insurance, loan program rules, homeowners-association requirements, property-specific taxes, and lender-specific debt treatment. A lower personal limit may be appropriate when income is variable or other expenses are likely to rise.
For an important decision, compare the output with original documents, lender or employer terms, supplier information, professional guidance, or other authoritative records relevant to the calculation. Small differences in rates, timing, fees and definitions can materially change a result even when the formula itself is correct.
Important assumptions and limitations
The model does not include mortgage insurance, closing costs, points, maintenance, utilities, special assessments, or local lending rules. Property tax is estimated as a percentage of home value. The calculator assumes a fixed-rate fully amortizing mortgage and does not model adjustable rates or temporary buydowns.
This calculator is for planning, checking, education and general informational use. It is designed to make assumptions visible and calculations reproducible, but it does not replace a contract, disclosure, professional opinion, medical assessment, accounting policy or lending decision.
Frequently asked questions
Why use two DTI limits?
Front-end DTI limits housing cost alone, while back-end DTI also includes other monthly debts. Using the tighter result helps avoid overstating affordability.
Does a bigger down payment always raise affordability?
Usually it does because it reduces the mortgage amount and loan-to-value. However, cash needed for closing costs and reserves should also be protected.
Is the result the same as pre-approval?
No. It is an independent planning estimate, not a lending decision or credit approval.