The real limit is what your lender will approve, not what feels comfortable

Your lender will approve you for a mortgage payment based on your debt-to-income ratio (DTI), which compares your total monthly debt payments to your gross monthly income. Most lenders cap this at 43 percent—meaning if you earn $5,000 a month before taxes, they will lend you enough so your mortgage payment plus other debts don't exceed $2,150. Some lenders go as high as 50 percent for borrowers with strong credit and savings, but 43 percent is the standard threshold.

What you can afford, however, is different from what a lender will approve. A lender cares whether you'll default; you need to care whether the payment leaves you broke. The gap between these two numbers is where most people get into trouble.

Key Takeaways

  • Lenders typically approve mortgages up to 43 percent of your gross monthly income, but this does not mean you should spend that much.
  • Your actual affordability depends on your down payment size, property taxes and insurance in your area, whether you have other debts, and how much emergency savings you keep.
  • A useful rule of thumb is to keep your mortgage payment (including taxes and insurance) below 28 percent of gross income, which gives you breathing room.
  • Use a mortgage calculator to see the real monthly cost, then subtract it from your take-home pay to see what remains for food, utilities, childcare, and emergencies.

How lenders calculate what they'll approve

Lenders use two ratios. The first is your front-end ratio: your mortgage payment (principal, interest, property taxes, homeowners insurance, and mortgage insurance if applicable) divided by your gross monthly income. Most lenders want this at 28 percent or lower. The second is your back-end ratio: all your monthly debt payments (mortgage, car loans, credit cards, student loans, child support) divided by gross income. This is where the 43 percent cap usually applies.

If you earn $6,000 a month gross and have $800 in existing debt payments (car loan, credit cards), a lender will approve a mortgage payment of around $1,780 to stay within 43 percent total debt. But that $1,780 includes property taxes and insurance, which vary wildly by location. In a high-tax area, the actual loan amount might be much smaller than you expect.

Your credit score, down payment size, and employment history also affect approval. A larger down payment (20 percent or more) means you avoid mortgage insurance and may get better terms. A lower credit score might push your DTI limit down to 40 percent or require a larger down payment.

The difference between approval and actual affordability

Being approved for a $400,000 mortgage does not mean you should take it. Approval assumes you will make the payment and nothing else will break. Affordability assumes life happens: your car needs a transmission, your child needs braces, your hours get cut, or your partner loses a job.

A practical affordability rule is to keep your mortgage payment (including taxes and insurance) at or below 28 percent of your gross income. This is tighter than the 43 percent lenders use, but it leaves room for other expenses and emergencies. If you earn $6,000 a month, aim for a payment of $1,680 or less, not the $2,580 a lender might approve.

You also need to account for costs beyond the payment: property maintenance (roof, plumbing, heating), homeowners association fees if applicable, utilities, and property taxes that may rise over time. A 30-year mortgage means you are locked into this payment for decades, even if your income drops or your circumstances change.

How to calculate your actual number

Start with your gross monthly income—the amount before taxes, not what hits your bank account. If you are self-employed or have variable income, use a conservative average from the past two years.

Multiply that by 0.28 to find your target mortgage payment (the front-end limit). This is the total payment including principal, interest, property taxes, insurance, and mortgage insurance if you put down less than 20 percent.

Next, list all your other monthly debt: car payments, student loans, credit card minimums, child support, alimony. Add these to your target mortgage payment. If the total exceeds 43 percent of your gross income, lower your mortgage target.

Use an online mortgage calculator to see what loan amount produces your target payment. Enter your down payment, expected interest rate, and loan term (usually 30 years). The calculator will show you principal and interest, but you must add property taxes and insurance separately—these vary by location and property value. Contact a local tax assessor's office or insurance agent for estimates.

What property taxes and insurance actually cost

Property taxes vary dramatically by state and county. In New Jersey, homeowners pay around 0.8 percent of home value annually; in Alabama, it's closer to 0.4 percent. A $300,000 home in New Jersey costs roughly $2,400 per year in property tax ($200 monthly), while the same home in Alabama costs $1,200 per year ($100 monthly).

Homeowners insurance also varies by location, home age, and coverage level. Expect $800 to $1,500 per year ($67 to $125 monthly) in most areas, but coastal properties and older homes cost more. Get quotes from at least three insurers before you commit to a purchase price.

If your down payment is less than 20 percent, you will also pay private mortgage insurance (PMI), which protects the lender if you default. PMI typically costs 0.5 to 1 percent of the loan amount annually, added to your monthly payment. On a $300,000 loan, that's $125 to $250 per month. PMI drops off once you reach 20 percent equity, but this takes years.

Account for your other expenses and emergencies

After you subtract your target mortgage payment from your take-home pay (what actually reaches your bank account after taxes), you need to cover food, utilities, childcare, transportation, insurance, phone, internet, and everything else. If you have $3,500 take-home and a $1,400 mortgage payment, you have $2,100 left for all other expenses and savings.

A useful check: can you cover three to six months of expenses in savings before you buy? If not, your mortgage payment is too high. Homeownership is expensive and unpredictable. A water heater fails, a roof leaks, or you face a job loss. Without a cushion, a single emergency becomes a default.

If you have student loans, car payments, or credit card debt, these reduce how much house you can actually afford. Paying down debt before you buy increases your approval amount and your actual safety margin.

When to use a mortgage broker or financial advisor

A mortgage broker can show you rates from multiple lenders and help you understand how different down payment sizes, loan terms, and interest rates affect your monthly payment. This is useful for comparing a 15-year mortgage (higher payment, less interest over time) against a 30-year mortgage (lower payment, more interest over time).

A financial advisor can help you think through the trade-off between buying now and waiting to save a larger down payment. Waiting six months to save an extra $20,000 might lower your monthly payment by $100 to $150 and eliminate PMI entirely, which is often worth the delay.

Neither of these professionals can tell you what you "should" afford—that is a personal decision based on your risk tolerance, job security, family plans, and what else you want to do with your money. But they can show you the numbers clearly.

Frequently Asked Questions

What if my income is irregular or I'm self-employed?

Lenders typically average your income over two years and may require tax returns, profit-and-loss statements, and bank statements to verify earnings. Use a conservative average—the lower of your last two years' income—when calculating what you can afford. This protects you if your income drops.

Does my student loan debt affect how much house I can afford?

Yes. Lenders count your student loan payment (or 0.5 percent of the outstanding balance if you're in income-driven repayment) toward your total debt. If you owe $50,000 in student loans with a $500 monthly payment, that $500 reduces the mortgage payment a lender will approve. Paying down student loans before you buy increases your home buying power.

Should I put down 20 percent to avoid mortgage insurance?

It depends on your interest rate and timeline. If mortgage rates are low and you can invest the down payment money at a higher return, a smaller down payment might make sense financially. But PMI costs money and doesn't build equity, so 20 percent eliminates a real expense. Calculate both scenarios with a mortgage calculator to see the total cost over 10 years.

What if I get approved for more than I think I can afford?

Trust your gut. Lender approval is based on your ability to make the payment, not your quality of life. If a payment feels too high when you run the numbers against your actual expenses, it is too high. You live with the payment for 30 years; the lender does not.

How much should I save before I buy?

Beyond your down payment, aim for three to six months of total living expenses (mortgage, taxes, insurance, utilities, food, childcare, transportation, everything). This covers emergencies without forcing you to miss a payment or go into debt. If you can't save this much, your mortgage payment is too high for your current situation.