Figuring out how much house you can afford is a lot like deciding how many slices of pizza you should eat. The brain says “stop,” but the hand keeps going. The difference is that a mortgage hangs around for 30 years, and so does the weight of a bad decision.
It’s not really about the asking price. It’s about how the monthly payment fits into your actual life, along with utility bills, car repairs, and the occasional trip to the dentist. Here’s how to work out your number with a realistic lens.
Start With Your Monthly Budget, Not a Price Tag
Before you browse listings, take a cold, honest look at your monthly cash flow. A lender will pre-approve you for an amount they think you can handle, but that number is based on gross income and a few other numbers. Your own budget is the real guide.
A common mistake is to treat the “mortgage payment” as just principal and interest. In reality, your housing costs include property taxes, homeowners insurance, and any HOA fees. Together, these are often called PITI, which stands for principal, interest, taxes, and insurance.
Say you bring home $6,000 a month after taxes and retirement contributions. You might be comfortable allocating $1,500 to PITI. On a $300,000 house with 20% down and a 6.5% interest rate, your principal and interest comes to about $1,516. Add $250 for property taxes and $120 for insurance, and you’re at $1,886. That’s 31% of your take-home pay, which many people would call tight.
Instead of relying only on a lender’s pre-approval figure, run the numbers yourself with a mortgage loan calculator to see whether that total monthly payment actually leaves you breathing room at the end of each month.
The 28/36 Rule: A Starting Point, Not a Ceiling
The classic guideline says your housing payment should be no more than 28% of your gross monthly income, and your total debts (housing plus student loans, car payments, credit cards) should stay under 36%. It’s a useful benchmark, but it’s not foolproof.
Let’s use an annual income of $80,000. That’s about $6,667 in gross monthly income. 28% of that is $1,867. So lenders might happily approve you for a loan with a $1,800 PITI payment. But if you already carry a $400 car loan and $300 in student loans, your total debt load is $2,500, which amounts to 37.5% of gross income. You’ve crossed the 36% line.
That doesn’t mean you won’t get approved. Some loan programs allow debt-to-income ratios up to 50% for strong borrowers. But it means the margin for error gets thin. One missed paycheck or a surprise medical bill can throw everything off balance.
Why Lenders Offer More Than You’d Expect
Lenders care about your ability to repay, but they also have a business to run. They review your credit score, employment history, and savings. A 780 credit score with a stable job history can push your DTI beyond normal limits. Just because they’ll say yes doesn’t mean you should take it. Your pre-approval letter is a ceiling, not a recommendation.
Your Down Payment Changes the Math
The 20% down payment is the gold standard because it removes private mortgage insurance (PMI). But it’s not the only option. A 10% down payment on a $300,000 house means a $270,000 loan, plus about $100 a month in PMI. A 5% down payment pushes the loan to $285,000 and bumps PMI to around $150 or more each month.
On the flip side, making a 25% down payment brings your monthly payment down and gives you a stronger equity position right away. The trade-off is tying up more cash that could have been invested elsewhere or kept as an emergency fund. You can see the impact of each down payment scenario in our step-by-step affordability breakdown, which walks through the math on several common situations.
Closing Costs Are Real Money
Your down payment is just the opener. Closing costs typically run 2% to 5% of the loan amount. On a $300,000 house, that’s $6,000 to $15,000 on top of your down payment. Some buyers ask the seller to cover a portion, or they fold the costs into the loan itself. That raises your monthly payment and the total interest you pay over 30 years.
Don’t Forget the One-Time and Ongoing Costs
Beyond PITI, a house has a way of asking for more. Here’s a realistic checklist to budget for:
- Maintenance: Set aside 1% of the home’s value each year. On $300,000, that’s $3,000 for new appliances, roof patches, and plumbing surprises.
- Utilities: Heat, cooling, water, and trash pickup often cost more than apartment living. Add $100 to $200 to your monthly variable costs.
- Homeowners insurance: The mortgage payment assumes this, but many people forget to include contents coverage or flood insurance if needed.
- HOA fees: If your neighborhood has a homeowners association, expect $50 to $500 per month depending on the amenities.
- Moving and furnishing: Curtains, lawnmowers, and that first emergency plumber visit can total $2,000 to $5,000.
- Property taxes: These often rise after a sale because the assessed value jumps to the purchase price.
Run the Numbers on Real Scenarios
Rather than guessing, plug your actual numbers into a mortgage loan calculator and adjust for different down payments, interest rates, and tax rates. It’s the fastest way to see the impact of a half-point rate difference or an extra $10,000 down.
For example, a single person earning $70,000 with no debts and a 720 credit score might be able to borrow up to $300,000. But a monthly payment of $1,900 on a take-home of $4,800 leaves little for retirement savings or an emergency fund. Even if you qualify for a larger loan, the real question is whether the payment leaves you with enough breathing room.
If you want a more detailed look at the entire process, read our step-by-step breakdown of how much house you can really afford. It goes through each calculation line by line, including debt-to-income ratios and loan limits for conventional and FHA loans.
The Credit Score and Debt Situation: Hidden Gatekeepers
Your credit score directly influences the interest rate you’re offered. Even a small difference matters. On a $250,000 loan, a 7% rate costs about $1,663 a month. Drop that to 6.5%, and you’re at $1,580. Over 30 years, that half-point gap equals roughly $30,000 in extra interest.
If your credit is under 700, it might be worth waiting a few months to improve it before buying. Pay down balances, dispute errors, and keep old accounts open. The same logic applies to your debt-to-income ratio. Lenders count the minimum payments on student loans and credit cards, not what you actually pay each month, so even small minimums matter.
A More Complete Way to Think About Affordability
Numbers help, but they don’t tell the whole story. A home that uses 28% of your gross income can still feel unaffordable if you have high medical costs, a side business with irregular income, or you’re contributing to a child’s education.
Think about the next five years. Are you planning to stay in the same city? Do you need more space for a family? A smaller down payment might leave you with a buffer for other goals. Also consider opportunity cost. That 20% down payment could be sitting in an index fund while you save and invest. Real estate builds equity, but the equity is hard to access until you sell.
Ultimately, the right amount to spend is the one that lets you sleep at night. If the monthly payment feels tight on paper, it will feel worse in real life. Use your numbers, ignore the lender’s ceiling, and decide based on the life you want to live.