Mortgage Affordability Calculator
Purchasing a home is likely the largest financial decision you will make in your lifetime. Before you start browsing listings and falling in love with properties, it is crucial to answer the question: "How much house can I actually afford?"
Our Mortgage Affordability Calculator uses the standard debt-to-income (DTI) ratios preferred by lenders to give you a realistic estimate of your purchasing power. By inputting your income, debts, and down payment, you can determine a safe budget that keeps your finances healthy.
Understanding How Affordability is Calculated
Lenders primarily use two ratios to determine how much money they are willing to lend you for a mortgage: the Front-End Ratio and the Back-End Ratio.
1. The Front-End Ratio (28% Rule)
This rule states that your total monthly housing costs should not exceed 28% of your gross monthly income. Housing costs include:
- Mortgage Principal and Interest
- Property Taxes
- Homeowners Insurance
- Homeowners Association (HOA) fees (if applicable)
Example: If your household earns $8,000 per month, your housing costs generally shouldn't exceed $2,240.
2. The Back-End Ratio (36% Rule)
The back-end ratio includes your housing costs plus all other monthly debt payments, such as:
- Car loans
- Student loans
- Credit card minimum payments
- Personal loans
Most conventional lenders prefer this total debt load to stay under 36% of your gross income, though some loan programs (like FHA) may allow higher ratios.
Factors That Impact Your Buying Power
Beyond your income, several variables significantly change the price of the home you can afford:
Interest Rates
Interest rates are the biggest lever in affordability. A 1% increase in interest rates can reduce your buying power by roughly 10%. When rates are low, your monthly payment covers more principal, allowing you to buy a more expensive home for the same monthly cost.
Down Payment
A larger down payment does two things: it reduces the loan amount (lowering monthly payments) and directly increases the maximum price you can pay. Aiming for 20% avoids Private Mortgage Insurance (PMI), which saves you money monthly.
Debt-to-Income (DTI)
Reducing your existing monthly debts is often the fastest way to increase your mortgage affordability. Paying off a $400/month car note can increase your mortgage borrowing power by approximately $60,000 to $70,000 (depending on current interest rates).
Frequently Asked Questions
Does this calculator include closing costs?
No, this calculator estimates the home price based on monthly cash flow. You should budget an additional 2% to 5% of the home purchase price for closing costs, which are paid upfront.
What if I have a low credit score?
If your credit score is lower (under 620), lenders may require a higher interest rate or a larger down payment, which will reduce your affordability. Improving your credit score before applying can save you thousands over the life of the loan.