Start with your gross monthly income and debt

The most practical way to find your mortgage ceiling is to use the debt-to-income ratio that lenders actually apply. Most conventional lenders will approve you for a mortgage if your total monthly debt payments—including the new mortgage payment—do not exceed 43% of your gross monthly income. Some lenders go as high as 50%, but 43% is the standard threshold.

To calculate this, first write down your gross monthly income. That is your income before taxes. If you earn $60,000 per year, your gross monthly income is $5,000. Next, list every monthly debt payment you currently make: car loans, student loans, credit cards (use the minimum payment, not the balance), personal loans, child support, anything with a fixed monthly obligation. Add them up.

Multiply your gross monthly income by 0.43. That is your maximum total monthly debt ceiling. Subtract your existing debt payments from that number. What remains is the maximum monthly mortgage payment a lender will typically allow you to carry.

Key Takeaways

  • Most lenders cap your total monthly debt at 43% of your gross income, which includes your new mortgage payment.
  • To find your maximum mortgage payment, multiply your gross monthly income by 0.43, then subtract your existing monthly debt payments.
  • A mortgage payment calculator can convert that monthly amount into a home price, but the result depends on interest rates, loan term, property taxes, and insurance in your area.
  • Your actual affordability is lower than your lender's maximum—aim to keep your housing payment to 28% of gross income if you want breathing room for other expenses.
  • Down payment size, credit score, and debt history all affect the interest rate you receive, which changes the home price you can afford by tens of thousands of dollars.

Convert your maximum payment into a home price

Once you know your maximum monthly mortgage payment, you need to convert it into a dollar amount you can borrow. This requires knowing three things: the interest rate you expect to receive, the loan term (usually 30 years), and your down payment size.

Use an online mortgage calculator—most banks and financial websites offer them free. Enter your maximum monthly payment, your expected interest rate, and your loan term. The calculator will show you the loan amount you can afford. If you plan to put 20% down, divide that loan amount by 0.80 to find the home price. If you plan to put 10% down, divide by 0.90.

The interest rate matters enormously. A $300,000 loan at 6% costs roughly $1,799 per month over 30 years. The same loan at 7% costs roughly $1,996 per month. That 1% difference adds $200 to your payment and means you can afford a home roughly $30,000 cheaper at the higher rate. Your credit score, down payment size, and debt history all affect the rate you receive, so get pre-approved by a lender to see what rate you actually may have access to for, not just what rates are advertised.

Account for property taxes, insurance, and HOA fees

Your mortgage payment itself is only part of your housing cost. Lenders include property taxes and homeowners insurance in the debt-to-income calculation, and they use a standard estimate: roughly 0.8% to 1.2% of the home's value per year for property taxes, depending on your state and county, plus $1,000 to $2,000 per year for insurance. These vary widely by location.

If you are buying in a neighborhood with a homeowners association, add that monthly fee to your housing costs as well. Some HOAs charge $100 per month; others charge $500 or more. Ask the seller or real estate agent for the HOA fee before you make an offer, because it directly reduces how much home you can afford.

To get accurate numbers, research property tax rates for the specific county and neighborhood you are considering. Your county assessor's office publishes this information online. For insurance, get quotes from at least two insurers for the type of home you are considering. Do not use a generic estimate—your actual costs may be significantly higher or lower.

The difference between what you can afford and what you should afford

Lenders will approve you for up to 43% of your gross income in total debt. That does not mean you should borrow that much. A more conservative approach is to keep your housing payment—mortgage, taxes, insurance, and HOA—to 28% of your gross monthly income. This leaves room for utilities, maintenance, repairs, and the rest of your life.

If your gross monthly income is $5,000, a 28% housing budget is $1,400 per month. A 43% total debt budget is $2,150 per month, but that includes car payments and student loans. The difference between these two numbers is the gap between what lenders think you can handle and what actually leaves you with financial breathing room.

Many people who stretch to their lender's maximum end up house-poor: they can make the payment, but they cannot save, they cannot handle a repair, and they cannot weather a job loss. Start with the 28% rule. If you want to go higher, do so deliberately, knowing what you are trading away.

How your down payment affects affordability

A larger down payment lowers your monthly payment and the total interest you pay, but it also means you need more cash upfront. A 20% down payment eliminates the requirement for private mortgage insurance (PMI), which typically costs 0.5% to 1% of the loan amount per year. A 10% down payment requires PMI; a 5% down payment requires more PMI.

If you put 10% down on a $300,000 home, you borrow $270,000 and pay PMI on top of your mortgage payment. That PMI might add $150 to $300 per month. If you put 20% down, you borrow $240,000 with no PMI. The monthly payment is lower, and you avoid PMI entirely. However, saving an extra $60,000 for a 20% down payment takes time, and waiting may not make sense if home prices are rising in your market or if you are paying high rent.

Some first-time buyers use down payment assistance programs through their state or local housing authority, or through nonprofits. These programs may offer grants or low-interest loans that count toward your down payment. Research what is available in your area before you assume you need to save the full amount yourself.

What happens after you know your number

Once you have calculated your affordable price range, get pre-approved by a lender. Pre-approval is different from pre-qualification: a pre-approval involves a credit check and verification of your income and assets. It shows sellers you are serious and gives you a firm number to work with when you start looking.

During pre-approval, the lender will verify your income, check your credit report, and ask about your debts. Be honest about everything. If you have recent late payments, collections, or high credit card balances, your interest rate will be higher, which lowers the home price you can afford. If you pay off debt or raise your credit score before applying, you may may have access to for a better rate.

Pre-approval is valid for 60 to 90 days, depending on the lender. After that, you will need a new pre-approval if you have not made an offer. Do not apply for new credit, take on new debt, or change jobs during this period—lenders re-verify everything before closing, and changes can delay or derail your loan.

Frequently Asked Questions

What if I have student loans or other debt I cannot pay off before buying?

Student loans, car payments, and other debts count against your debt-to-income ratio even if you are not paying them down aggressively. If your existing debt is high, your maximum mortgage payment is lower. You can still buy, but you may need to look at homes in a lower price range, or you can wait and pay down debt first to improve your ratio.

Does my spouse's income count if we are buying together?

Yes. If you are married or in a registered domestic partnership, most lenders will combine your incomes and debts for the calculation. If you are unmarried, the lender will typically look at each person's income and debt separately, though some lenders allow co-borrowers. Ask your lender how they handle your specific situation.

What if the interest rate changes between pre-approval and closing?

Interest rates move daily. Your pre-approval is based on the rate you were quoted on that day. If rates rise before you close, your monthly payment will be higher, and you may need to lower your offer price or increase your down payment to stay within your budget. Some lenders offer rate locks that hold your rate for 30 to 60 days for a fee. Ask about this when you get pre-approved.

Can I afford a home if I am self-employed?

Yes, but the process is more involved. Lenders typically ask for two years of tax returns and may average your income over that period if it has been variable. Some lenders specialize in self-employed borrowers. Start by talking to a mortgage broker who works with self-employed clients, because they know which lenders are fastest and most flexible with documentation.

Should I max out my budget or stay below it?

Stay below it. Lenders approve you for the maximum you can technically carry, but that leaves no room for emergencies, job changes, or major repairs. A home that costs 28% of your gross income is more sustainable than one that costs 43%. You will sleep better, save more, and be more resilient if something goes wrong.