Mortgage Affordability Calculator
Enter your income, other debts and down payment to see the loan and home price you can likely afford under the common 28%/36% guideline.
These are estimates using standard formulas (loan amortization and the common 28%/36% guideline). They are not financial or real-estate advice — confirm any number with a lender or broker.
How the numbers are calculated
Affordability uses the common 28%/36% guideline: your housing payment should stay under 28% of gross monthly income, and total debt payments under 36%. The calculator turns that into a maximum loan and a maximum home price.
General housing facts
Home prices and property-tax rates vary a lot by location. The mortgage payment is mostly principal and interest, but taxes, insurance, maintenance and PMI often add 20–40% on top. Local prices and taxes change year to year, so always get a formal quote from a lender and check current listings.
Worked examples
Example: single buyer, $120,000 income
With $120,000 gross income, no other debt and 20% down, the 28% guideline allows about $2,800 a month for housing. At 6.8% over 30 years that supports roughly a $430,000 loan, or about a $537,000 home price after the down payment. The calculator prints both the max loan and the max price.
Example: couple, $180,000 income, $600 other debt
At $180,000 income with $600 a month of other debt, the 36% back-stop limits total debt payments to $5,400 a month, so housing is capped near $4,200 a month. That supports roughly a $644,000 loan and about an $805,000 price — well below the no-debt case, a reminder that car loans and cards directly shrink your home budget.
The 28%/36% rule explained
The 28% front-end rule says housing should stay under 28% of gross monthly income. The 36% back-end rule says all debt payments together should stay under 36%. Lenders use both; the calculator takes the stricter of the two, which is why adding other debt reduces the number.
Where the down payment fits
The down payment does not change the loan you qualify for, but it changes the home price you can reach: a bigger down payment turns the same loan into a more expensive house, or the same house into a smaller loan. Enter yours above to see both the max loan and the resulting max price.
When this calculator does not apply
The 28%/36% guideline is a screen, not an approval. Lenders also check credit score, job history and cash reserves, and some loan programs allow higher ratios. Treat the output as a planning ceiling, not a promise.
Data sources & last update
Tax rates and home prices are typical published values (Tax Foundation, FHFA, state revenue departments, Insurance Information Institute) and are examples updated for 2026. They are not a quote — confirm current figures with a lender or local assessor before acting. HomeMath runs entirely in your browser; nothing you type is uploaded.
Frequently asked questions
How does the down payment affect affordability?
The down payment does not change the loan you qualify for under the income rules, but it changes the home price you can buy: a larger down payment reaches a pricier home for the same loan, or a cheaper home with a smaller loan.
What is the debt-to-income limit?
It is the 36% back-end rule: your total monthly debt payments (housing plus cards, car loans and others) should stay under 36% of gross income. The calculator applies it automatically and uses the stricter of the 28% and 36% limits.