Start with your debt-to-income ratio and down payment

Most lenders will not lend you more than 43 percent of your gross monthly income (before taxes) when you add your new mortgage payment to all other debts — car loans, student loans, credit cards, child support. This is called your debt-to-income ratio, or DTI. If you earn $5,000 a month before taxes and have $800 in other monthly debt payments, lenders will typically cap your mortgage payment at around $1,350 ($5,000 × 0.43 − $800). A mortgage payment of $1,350 usually means you can borrow somewhere between $250,000 and $300,000, depending on interest rates and loan length — but that assumes you have a down payment saved.

Your down payment is the cash you bring to closing. The larger it is, the smaller the loan you need. A 20 percent down payment on a $300,000 house is $60,000; a 5 percent down payment is $15,000. If you have $30,000 saved, you can afford a house around $150,000 with 20 percent down, or around $315,000 with 10 percent down (though 10 percent down usually means you will pay mortgage insurance, which raises your monthly cost). Your down payment is often the real ceiling, not the lender's math.

Key Takeaways

  • Lenders typically cap your mortgage payment at 43 percent of your gross monthly income minus your other debt payments, but this is a maximum, not a target.
  • Your down payment often matters more than the lender's calculation — if you have $30,000 saved, that limits what you can afford more than your income does.
  • A mortgage payment includes principal, interest, property taxes, homeowners insurance, and possibly mortgage insurance, so the advertised interest rate does not tell you the full monthly cost.
  • Use a mortgage calculator to convert a monthly payment you can afford into a house price, working backward from your budget rather than forward from a lender's offer.
  • Getting pre-approved by a lender shows you the actual number they will lend, but pre-approval is not the same as what you should spend.

Calculate your actual monthly payment, not just the interest rate

A mortgage payment is not just interest. It includes principal (the amount borrowed), interest, property taxes, homeowners insurance, and possibly private mortgage insurance (PMI) if your down payment is less than 20 percent. Property taxes vary wildly by location — a $300,000 house in New Jersey might cost $500 a month in property tax, while the same house in Alabama might cost $150. Homeowners insurance ranges from $100 to $300 a month depending on the house and your location. PMI typically costs 0.5 to 1 percent of the loan amount per year, divided into monthly payments.

A mortgage calculator that includes taxes and insurance will show you the real number. If you search "mortgage calculator," most will let you enter your down payment, loan amount, interest rate, your state or county (for tax estimates), and whether you need PMI. The result is your actual monthly payment. Work backward: if you can afford $1,500 a month, enter that into the calculator and adjust the loan amount until the total payment matches. That tells you the house price you can actually afford, not the price a lender says you can borrow.

Account for property taxes and insurance before you shop

Property taxes are set by your county or municipality and do not change based on your income or credit score. If you are shopping in a new area, look up the tax rate before you fall in love with a house. County assessor websites usually list the rate as a percentage of home value. A 1 percent tax rate on a $300,000 house is $3,000 a year, or $250 a month. A 2 percent rate is $500 a month — that is a $3,000 annual difference that will not show up in the interest rate.

Homeowners insurance quotes vary by house age, roof condition, location (flood risk, crime rate), and your claims history. Get a quote from your current insurance company or a new one before you make an offer. Do not assume the seller's insurance cost applies to you — your rate depends on your profile. Adding $200 a month for insurance to your budget is safer than discovering after closing that your actual cost is $350.

Understand what pre-approval actually means

A pre-approval letter from a lender says they will lend you up to a certain amount based on your income, credit score, and debts at the time you applied. It is not a promise — it is a conditional offer. The lender will verify your income again before closing, pull your credit report again, and check that you have not taken on new debt. If you buy a car or run up credit cards between pre-approval and closing, the lender can reduce the amount or walk away.

Pre-approval also does not mean you should borrow the full amount. A lender approved you for $350,000 because your income supports it mathematically, not because $350,000 is comfortable for your life. If your monthly payment at that price leaves you $200 after all other expenses, you are one car repair away from missing a payment. Pre-approval is a ceiling, not a recommendation.

Build in a buffer for maintenance, repairs, and rising rates

Homeownership costs more than the mortgage payment. A roof lasts 20 to 25 years, a water heater 10 to 15 years, an HVAC system 15 to 20 years. If you buy a $300,000 house with a $250,000 mortgage, you should budget $250 to $500 a month for maintenance and eventual replacements — that is $3,000 to $6,000 a year. Many people do not, and then a $12,000 roof replacement forces them to take on debt or sell.

If you are getting an adjustable-rate mortgage (ARM), your interest rate will rise after the fixed period ends. A 3 percent rate on a $250,000 loan is about $1,060 a month in principal and interest; a 5 percent rate is about $1,340. If your budget is tight at 3 percent, you cannot afford the house. If you are getting a fixed-rate mortgage, your payment stays the same, but your property taxes and insurance will still rise over time. Budget for that too.

Compare what you can afford to what is actually for sale

Your calculation might say you can afford a $280,000 house, but the market in your area might have nothing under $350,000. At that point, you have three choices: save a larger down payment, move to a different area, or wait for the market to shift. None of these is wrong, but pretending the math works when it does not will leave you house-poor or unable to close.

Look at what is actually listed in your target neighborhoods and price ranges. If a $280,000 house is rare and $350,000 is common, you are shopping in the wrong price range for your budget. Adjust your target price down, or adjust your down payment up, or both. The market does not care what a calculator says you can afford.

Frequently Asked Questions

What if I have a lot of student loan debt — does that prevent me from getting a mortgage?

Not automatically, but it reduces how much you can borrow. Student loans count toward your debt-to-income ratio. If you owe $400 a month in student loans and earn $5,000 a month, lenders will cap your mortgage payment at around $1,150 ($5,000 × 0.43 − $400). You can still get a mortgage; you just may have access to for a smaller one. Paying down student loans before you buy will increase your borrowing power.

Does a co-signer help me afford a more expensive house?

Yes, if the co-signer's income is added to yours for the debt-to-income calculation. A co-signer with a $6,000 monthly income and no other debt can increase your borrowing power by roughly $2,580 a month in mortgage payment capacity. However, the co-signer is legally responsible for the loan if you do not pay, and it counts as their debt too — it will affect their ability to borrow for their own needs.

Should I aim for the maximum the lender will give me?

No. The maximum is what the lender will lend; it is not what you should spend. If you borrow the maximum, you have no cushion for job loss, medical emergencies, or market downturns. Most financial advisors suggest keeping your housing payment to 28 percent of gross income or less, which is lower than the 43 percent lenders allow. That leaves room for everything else.

What if interest rates drop after I lock in my rate?

You can refinance — take out a new loan at the lower rate to pay off the old one. Refinancing has closing costs (usually 2 to 5 percent of the loan amount), so it only makes sense if the rate drop is large enough to save you money over time. If rates drop 0.5 percent, refinancing might not be worth it; if they drop 1.5 percent, it usually is. A mortgage lender can calculate the break-even point for you.

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

Yes, but lenders require more documentation. Most want to see two years of tax returns and may average your income over that period if it varies. Some want to see a profit-and-loss statement from your accountant. Self-employed borrowers often may have access to for less than W-2 employees with the same gross income because lenders are more cautious about income stability. Start the conversation with a lender early so you know what documents to gather.