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Mortgage Affordability Calculator

Determine how much house you can reasonably afford based on your income, debts, and current mortgage rates using standard lender debt-to-income (DTI) ratios.

(Car loans, student loans, minimum credit card payments, etc.)

Understanding How Much House You Can Afford

Determining "how much house can I afford" is the crucial first step in the homebuying process. It goes beyond looking at house prices online; it requires understanding how lenders view your financial profile. This calculator uses standard industry "Debt-to-Income" (DTI) ratios to give you a realistic estimate of your purchasing power.

The Critical Role of Debt-to-Income (DTI) Ratios

Lenders don't just look at your salary. They look at how much of your salary is already committed to other debts. They use two primary ratios to determine mortgage affordability:

  • The Front-End Ratio (Housing Ratio): This is the percentage of your gross monthly income that would go toward housing costs. Housing costs include Principal, Interest, Property Taxes, and Homeowners Insurance (PITI). Lenders typically prefer this ratio to be 28% or lower.
  • The Back-End Ratio (Total Debt Ratio): This is the most critical number. It is the percentage of your gross monthly income that goes toward all your monthly debt obligations, including the new mortgage payment, plus credit card minimums, car loans, and student loans. Most conventional lenders prefer this ratio to be 36% or lower, though some loan programs allow higher ratios.

How the Calculation Works in Practice

Let's look at a realistic example of how these ratios impact affordability. Imagine a household with a gross annual income of $96,000 (that's $8,000 per month).

  1. Calculate the Back-End Limit: Using a conservative 36% back-end limit, the total allowable monthly debt is $8,000 * 0.36 = $2,880.
  2. Account for Existing Debt: If this household has a $400 car payment and $200 in student loans (total $600 monthly debt), this amount is subtracted from the limit. $2,880 – $600 = $2,280.
  3. Determine Max Housing Payment: This remaining $2,280 is the maximum allowed for the new mortgage PITI payment, provided it doesn't exceed the front-end ratio limit (which would be $8,000 * 28% = $2,240). In this case, the front-end ratio ($2,240) is slightly more limiting.

The calculator then works backward from this maximum monthly payment, factoring in your down payment and current interest rates, to determine the total home price you can afford.

Interest Rates and Buying Power

The interest rate is a major variable in your affordability. As rates rise, the cost of borrowing increases, meaning your monthly payment buys less "house." A 1% increase in interest rates can significantly reduce your maximum purchasing power, even if your income and down payment remain the same. This is why locking in a rate is a critical step once you are under contract on a home.

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