Mortgage Affordability Calculator

The Mortgage Affordability Calculator is a free online tool that estimates how much house you can afford before you start shopping. Enter your annual income, your monthly debts, and your planned down payment, and the tool instantly reports three figures: the home price within your reach, the estimated monthly mortgage payment, and the maximum loan amount you could likely borrow. Whether you are a first-time buyer or planning your next move, these three numbers turn a vague budget into a concrete price range.

Buying a home is the largest purchase most people ever make, and the most expensive mistake is falling in love with a house you cannot comfortably afford. Lenders use well-established guidelines to decide how much to lend, and understanding those guidelines before you talk to a bank puts you in control of the conversation. This page explains the rules lenders apply, walks you through two fully worked examples, and answers the questions buyers ask most, so you can use the Mortgage Affordability Calculator with complete confidence.

The 28/36 Rule Lenders Use

Most mortgage lenders evaluate affordability with two ratios known as the 28/36 rule. The first number, 28 percent, is the front-end ratio: your total monthly housing payment, including principal, interest, taxes, and insurance, should generally not exceed 28 percent of your gross monthly income. The second number, 36 percent, is the back-end ratio: your total monthly debts, including the housing payment plus car loans, student loans, and minimum credit card payments, should generally not exceed 36 percent of gross monthly income.

The calculator applies both limits and uses whichever produces the smaller payment. If you carry little debt, the 28 percent housing rule sets your budget. If you carry heavy debt, the 36 percent total-debt rule becomes the binding constraint and lowers what you can borrow. This mirrors how underwriters actually think: they care about your whole debt picture, not just the mortgage in isolation.

These are guidelines, not laws. Some loan programs allow higher ratios, especially with strong credit and large down payments, while conservative buyers deliberately stay below them for breathing room. But as a starting estimate, the 28/36 rule is the industry standard and the right foundation for planning.

How the Three Results Are Computed

The calculator works in three steps. First, it converts your annual income to monthly income and computes the two payment ceilings: 28 percent of monthly income, and 36 percent of monthly income minus your monthly debts. It takes the smaller of the two as your affordable monthly payment, the second result.

Second, it converts that monthly payment into a maximum loan amount using standard 30-year mortgage math at a 7 percent interest rate. The conversion uses the exact amortization formula, the same one lenders use, so the loan figure reflects what that payment truly supports over 360 monthly payments.

Third, it adds your down payment to the maximum loan to produce the affordable home price, the first result. A larger down payment directly raises the price you can afford without raising the monthly payment, which is why saving for a down payment is the highest-leverage move a buyer can make.

How to Use the Mortgage Affordability Calculator

Three honest inputs produce a realistic price range. Gather your figures from pay stubs and debt statements, then calculate.

1. Enter your annual income in dollars, your gross yearly earnings before taxes, for example 90000.
2. Enter your monthly debts in dollars, the minimum payments on car loans, student loans, and credit cards, for example 500. Do not include rent or utilities.
3. Enter your down payment in dollars, the cash you plan to put down, for example 40000.
4. Click Calculate to see your affordable home price, estimated monthly payment, and maximum loan amount.
5. Click Reset to clear the form and test a different income, debt level, or down payment.

Worked Example 1: $90,000 Income, $500 Debts, $40,000 Down

Suppose the Rivera household earns $90,000 per year, pays $500 monthly toward a car loan and credit cards, and has saved a $40,000 down payment. They want their realistic price range.

1. They enter 90000 as annual income, 500 as monthly debts, and 40000 as the down payment, then click Calculate.
2. The tool converts income to $7,500 monthly. The 28 percent ceiling is $2,100; the 36 percent ceiling is $2,700 minus $500 in debts, or $2,200. The smaller, $2,100, becomes the estimated monthly payment.
3. At 7 percent over 30 years, a $2,100 monthly payment supports a maximum loan of about $315,600.
4. Adding the $40,000 down payment gives an affordable home price of about $355,600.
5. The Riveras now know to shop in the mid-$300,000s, with a monthly payment near $2,100 before taxes and insurance.

Because their debts are modest, the 28 percent housing rule binds. If their debts were much higher, the 36 percent rule would take over and shrink the price range, which the calculator would show automatically.

Worked Example 2: $130,000 Income, $1,400 Debts, $60,000 Down

Now consider a buyer earning $130,000 with heavier obligations: $1,400 in monthly student loan and car payments, plus a $60,000 down payment saved.

1. She enters 130000 as annual income, 1400 as monthly debts, and 60000 as the down payment, then clicks Calculate.
2. Monthly income is about $10,833. The 28 percent ceiling is about $3,033; the 36 percent ceiling is $3,900 minus $1,400, or $2,500. The debts bind, so the estimated monthly payment is $2,500.
3. At 7 percent over 30 years, a $2,500 payment supports a maximum loan of about $375,700.
4. Adding the $60,000 down payment gives an affordable home price of about $435,700.
5. She learns that paying down debts would raise her price range faster than saving more, since the 36 percent rule is her constraint.

This example reveals a strategic insight: when debts bind your affordability, every $100 of monthly debt you eliminate can unlock roughly $15,000 of additional home price. Debt payoff before house hunting often beats a bigger down payment.

Down Payment: Why 20 Percent Is the Magic Number

Putting down 20 percent of the purchase price has long been the benchmark, and for good reason. At 20 percent down, most lenders waive private mortgage insurance (PMI), a monthly charge that protects the lender, not you, and typically costs 0.5 to 1 percent of the loan amount per year. On a $300,000 loan, PMI can add $125 to $250 to every monthly payment until you build enough equity to drop it.

Below 20 percent, buying is still very possible. Conventional loans allow as little as 3 percent down for qualified buyers, and government programs go further: FHA loans allow 3.5 percent, VA loans allow zero down for eligible veterans, and USDA loans allow zero down in qualifying rural areas. The trade-off is PMI or equivalent fees plus a larger loan balance, meaning higher monthly payments and more interest over time.

The calculator treats any down payment you enter the same way, adding it to the maximum loan. Run it with 10 percent down and with 20 percent down on the same price to see exactly how much PMI-free buying saves you each month.

What the Estimate Leaves Out

An honest affordability estimate must acknowledge what the simplified math does not include. The calculator's monthly payment covers principal and interest only. Your real housing payment will also include property taxes, homeowners insurance, and possibly PMI and HOA dues, collectively known as PITI plus extras. In high-tax areas, taxes and insurance can add 30 to 50 percent on top of principal and interest.

Credit score matters enormously and the calculator assumes a standard qualifying profile. A higher score earns a lower rate, which directly raises the loan your payment supports; a lower score does the opposite and can even block approval. The 7 percent rate assumption is a planning figure, so check current market rates and rerun your thinking with the real number when you get pre-approved.

Finally, affordability guidelines describe what lenders will allow, not what will feel comfortable. Childcare, medical costs, and lifestyle spending do not appear in the 28/36 math. Many happy homeowners deliberately buy below their maximum, keeping the payment near 20 to 25 percent of income so the house enriches life instead of constraining it.

Beyond the Payment: The True Cost of Ownership

The monthly mortgage payment is only the largest line in a longer list. Budget planners recommend setting aside about 1 percent of the home's value per year for maintenance, more for older homes, plus reserves for the big-ticket replacements: roof, HVAC, and appliances each arrive on their own schedule and each costs thousands.

Closing costs deserve their own line in your plan. Buyers typically pay 2 to 5 percent of the purchase price at closing for lender fees, title insurance, appraisals, and prepaid taxes and insurance. On a $350,000 home, that is $7,000 to $17,500 due on closing day, separate from the down payment, and it must be saved in cash.

None of this argues against buying; it argues for planning with eyes open. Add estimated taxes, insurance, maintenance, and closing costs to the calculator's payment figure, and you have a genuinely complete picture of what ownership costs per month and per year.

Tips for Getting Accurate Results

1. Use gross income, not take-home pay. Lender ratios are based on pre-tax income. Using take-home pay understates what you can borrow.
2. Count every minimum debt payment. Include car loans, student loans, and credit card minimums. Omitting debts inflates the estimate and sets you up for a denial.
3. Do not include rent or utilities in debts. The ratios measure non-housing debt; the housing payment is computed separately by the tool.
4. Enter the down payment you will actually have. Use saved cash plus any gift funds you are certain of, not a hoped-for figure. The price range moves dollar for dollar with it.
5. Treat the result as a ceiling, not a target. Shopping 10 to 20 percent below your maximum leaves room for taxes, insurance, maintenance, and life.
6. Recalculate when rates move. The tool assumes 7 percent. If market rates are much higher or lower when you shop, get pre-approved and use the lender's real payment figure.
7. Pay down binding debts first. If the 36 percent rule constrains you, eliminating a monthly payment often raises your price range more than saving the same dollars for a down payment.

Frequently Asked Questions

1. What does the Mortgage Affordability Calculator calculate?

It calculates three results from your income, debts, and down payment: the home price you can likely afford, the estimated monthly mortgage payment under 28/36 guidelines, and the maximum loan amount that payment supports on a 30-year loan at 7 percent.

2. What is the 28/36 rule?

It is the standard lender guideline that housing costs should not exceed 28 percent of gross monthly income and total debts should not exceed 36 percent. The calculator applies both and uses whichever gives the smaller payment.

3. Does the monthly payment include taxes and insurance?

No. The estimated payment covers principal and interest only. Add property taxes, homeowners insurance, PMI if applicable, and HOA dues to get your true monthly housing cost.

4. Why does the calculator assume a 7 percent rate?

Seven percent is a reasonable planning rate for a 30-year fixed mortgage in recent markets. Actual rates vary daily with the market and your credit profile, so treat the figure as an estimate and confirm with a lender's pre-approval.

5. How does my down payment affect affordability?

Dollar for dollar: every extra down payment dollar raises the affordable home price by a dollar without changing the monthly payment. Larger down payments also reduce or eliminate PMI and lower total interest paid.

6. What is PMI and when do I pay it?

Private mortgage insurance protects the lender when your down payment is below 20 percent. It typically costs 0.5 to 1 percent of the loan per year, added to your monthly payment, and can usually be removed once you reach 20 percent equity.

7. Can I afford a house with student loan debt?

Yes, as long as your total debts fit within the 36 percent back-end ratio. Heavy student loan payments shrink the price range, so paying them down before buying is often the fastest way to raise it.

8. Should I buy at my maximum affordable price?

Most advisors say no. Buying below your maximum leaves room for taxes, insurance, maintenance, and unexpected life costs. A payment near 20 to 25 percent of income feels comfortable for most households.

9. What credit score do I need?

Conventional loans typically want 620 or higher, with the best rates reserved for scores in the mid-700s and above. FHA loans allow lower scores with a larger down payment. Your score directly affects your rate and therefore your affordable price.

10. Are closing costs included?

No. Closing costs of 2 to 5 percent of the price are due in cash at closing, separate from the down payment. Budget for them alongside the down payment when planning your cash needs.

11. What if my debts leave no room for a payment?

The calculator will tell you so. The fix is to pay down monthly debts, increase income, or both, then rerun the numbers. Reducing a single large minimum payment can unlock meaningful borrowing power.

12. Does the calculator work for 15-year loans?

It is calibrated for 30-year loans. A 15-year loan at the same payment supports a smaller loan amount but builds equity far faster and charges much less total interest. Ask a lender to run both scenarios when you are ready.

13. How do property taxes affect my budget?

Significantly and unevenly: tax rates vary widely by location. In high-tax areas, monthly escrow for taxes can rival the principal and interest payment itself. Always add local taxes to the calculator's payment figure.

14. Should I get pre-approved before house hunting?

Yes. Pre-approval confirms what a real lender will offer based on verified income, debts, and credit, and it makes your offers far stronger with sellers. Use the calculator for planning, then get pre-approved for certainty.

15. Can affordability change after I calculate?

Absolutely. Rate movements, income changes, new debts, and growing savings all shift the numbers. Rerun the calculator whenever any input changes so your price range stays current.

CONCLUSION

The Mortgage Affordability Calculator converts your income, debts, and down payment into the three numbers every buyer needs: an affordable home price, a realistic monthly payment, and a maximum loan amount. Built on the same 28/36 guidelines lenders use, it keeps your house hunt grounded in math instead of wishful thinking. Enter your figures, shop within the range it gives you, and step into homeownership with a payment your budget can carry comfortably for years.