The basic rule: lenders look at your income and existing debt
Most mortgage lenders use two numbers to decide how much they will lend you. The first is your debt-to-income ratio — the percentage of your monthly income that goes toward debt payments. The second is how much of your income can go toward the mortgage payment itself, including property taxes, insurance, and homeowners association fees if there is one.
Lenders typically want your total monthly debt payments (car loans, credit cards, student loans, and the new mortgage) to be no more than 43 percent of your gross monthly income. Some lenders will go to 50 percent if you have a strong credit score and savings, but 43 percent is the standard. The mortgage payment alone usually cannot exceed 28 percent of your gross income.
These are not rules written in law. They are the thresholds most banks use because they predict which borrowers will default. If you earn $5,000 a month gross, a lender will typically cap your total debt at $2,150 a month, with the mortgage payment itself at $1,400.
Key Takeaways
- Lenders limit your mortgage payment to roughly 28 percent of your gross monthly income and your total debt payments to 43 percent, though these thresholds vary by lender and credit profile.
- The price you can afford depends on your down payment size, local interest rates, and the length of your loan — the same income supports different house prices under different conditions.
- Your existing debt (car loans, credit cards, student loans) directly reduces how much house you can afford by eating into your debt-to-income allowance.
- A mortgage pre-qualification from a lender shows you a realistic number based on your actual finances, not a general calculator.
- The maximum a lender will offer you is not the same as the maximum you should borrow — your personal budget and emergency savings matter more than the lender's limit.
How down payment size changes what you can afford
The larger your down payment, the smaller the loan you need, and the smaller your monthly payment. A 20 percent down payment on a $300,000 house means you borrow $240,000. A 5 percent down payment on the same house means you borrow $285,000. The monthly payment difference is substantial.
If you have saved $40,000 and are looking at houses in a market where the median price is $350,000, you have a 11 percent down payment. If you are looking at houses priced at $200,000, you have a 20 percent down payment. The same savings changes your buying power depending on the price range you are shopping in.
Down payments below 20 percent trigger private mortgage insurance (PMI), an extra monthly fee that protects the lender if you default. PMI typically costs 0.5 to 1.5 percent of your loan amount per year, added to your monthly payment. This fee disappears once you have paid down the loan to 80 percent of the home's value, but it increases your monthly cost in the meantime.
Interest rates and loan length affect your monthly payment
Two borrowers with the same income and down payment can afford different house prices if interest rates have changed or they choose different loan lengths. A 30-year mortgage at 6 percent interest costs less per month than a 30-year mortgage at 7 percent on the same loan amount. A 15-year mortgage at 6 percent costs more per month than a 30-year mortgage at 6 percent on the same amount.
Interest rates change daily and depend on the broader economy, the Federal Reserve's decisions, and your credit score. You cannot control the rate environment, but you can control whether you choose a 15-year or 30-year loan. A 30-year loan keeps your monthly payment lower, which means you can afford a higher purchase price under the lender's 28 percent rule. A 15-year loan builds equity faster but requires a higher monthly payment.
When you get a pre-qualification from a lender, they will show you what you can afford at current rates. If rates drop before you close, your affordability goes up. If rates rise, it goes down.
Your existing debt reduces your buying power directly
If you have a car loan, credit card balances, or student loans, those payments count against your 43 percent debt-to-income limit. A $400 car payment and a $200 minimum on credit cards means you have already used $600 of your allowance before the mortgage payment is even calculated.
If you earn $5,000 a month gross, your 43 percent limit is $2,150 in total debt. If you already have $600 in other debt, you have $1,550 left for the mortgage payment. That $1,550 supports a much smaller loan than if you had no other debt.
Paying down or paying off existing debt before you apply for a mortgage directly increases the house price you can afford. This is one of the few things you can control before you start shopping. Paying off a $300 monthly car loan increases your available mortgage payment by $300 a month, which typically translates to $50,000 to $70,000 more in borrowing power, depending on interest rates.
What a pre-qualification actually tells you
A mortgage pre-qualification is a lender's estimate of how much they will lend you based on information you provide about your income, debts, and credit. It is not a promise. The lender has not verified your income documents, checked your employment, or ordered a property appraisal. A pre-qualification is useful because it gives you a realistic number to shop with, but it is not final.
A pre-approval is more thorough. The lender verifies your income with tax returns and pay stubs, pulls your credit report, and confirms your employment. A pre-approval is closer to a real commitment, though the lender can still back out if your financial situation changes or the property appraises below the purchase price.
Both pre-qualification and pre-approval are free and do not obligate you to borrow from that lender. You can get pre-may have access to or pre-approved from multiple lenders to compare their offers.
The difference between what you can afford and what you should borrow
A lender's maximum offer is based on risk to the bank, not on what is safe for your household budget. A lender will lend you up to 43 percent of your gross income in total debt because that is statistically where defaults start to rise. That does not mean you should borrow that much.
Your actual budget depends on your local cost of living, your job security, how much you have saved for emergencies, and how much you want to spend on housing versus other goals. If you have three months of expenses in savings and a job that could disappear in a downturn, borrowing at the lender's maximum leaves you vulnerable. If you have a year of expenses saved and stable income, you have more room.
A common guideline is that housing should not exceed 30 percent of your gross income, which is lower than the lender's 28 percent mortgage-only threshold. This leaves you room for property taxes, insurance, and maintenance without stretching your budget. The 43 percent total debt limit is also a ceiling, not a target.
How to estimate what you can afford without a calculator
Start with your gross monthly income — the number before taxes. Multiply it by 0.28 to find the maximum lender will allow for your mortgage payment alone. Multiply it by 0.43 to find the maximum for all debt combined. Subtract your existing monthly debt payments from that 43 percent number. What is left is available for the mortgage.
Once you have a monthly payment target, a lender can tell you what loan amount that supports. The loan amount depends on interest rates and loan length, which change, so this is an estimate. A $1,400 monthly payment at 6 percent interest over 30 years supports a loan of roughly $235,000. At 7 percent, the same payment supports roughly $215,000. At 5 percent, it supports roughly $260,000.
Add your down payment to the loan amount to find the house price. If you can put down $50,000 and the loan supports $235,000, you can afford a $285,000 house. If rates rise and the loan supports $215,000, you can afford a $265,000 house with the same down payment.
Frequently Asked Questions
Can I afford a house if I have student loan debt?
Yes, but the monthly payment counts against your debt-to-income ratio. If your student loan payment is $300 a month, that reduces the mortgage payment the lender will allow. Paying down the loan before you apply increases your buying power, but many people buy homes while still repaying student loans.
What if my income varies month to month?
Lenders typically average your income over the past two years if you are self-employed or work on commission. If your income has been rising, they may use a lower average to be conservative. Bring two years of tax returns and recent pay stubs so the lender can see the actual pattern.
Does my credit score affect how much I can borrow?
Credit score affects the interest rate you receive and sometimes the down payment requirement, but it does not directly change the debt-to-income limits. A lower credit score means a higher interest rate, which means your monthly payment is higher on the same loan amount, so you can afford less. A higher score gets you a lower rate and more buying power.
What if I want to borrow less than the lender offers?
You can always borrow less than the maximum. Some people choose to buy a less expensive house to keep their housing costs lower, build savings faster, or have more flexibility if their income drops. The lender's maximum is a ceiling, not a requirement.
How do property taxes and insurance affect affordability?
Property taxes and homeowners insurance are part of your monthly housing payment and count toward the 28 percent limit. A house in a high-tax area or with high insurance costs reduces the loan amount you can afford compared to the same house in a low-tax area. Ask a lender to estimate these costs for the specific house you are considering.