The Two Numbers That Matter
When figuring out how much house you can afford, there are two numbers to understand:
- What a lender will approve you for — based on your income, debts, and credit score
- What you can comfortably afford — based on your actual lifestyle, savings goals, and financial priorities
These two numbers are often very different. Lenders are in the business of lending money, and they'll often approve you for more than is wise for your personal financial situation. Just because you can qualify for a $500,000 mortgage doesn't mean you should take one.
How Lenders Calculate Your Maximum Loan
Lenders use your debt-to-income ratio (DTI) as the primary measure of how much they'll lend you. DTI compares your monthly debt payments to your gross monthly income.
There are actually two DTI ratios lenders look at:
- Front-end ratio (housing ratio) — your total monthly housing costs (mortgage payment, taxes, insurance, PMI, HOA) divided by your gross monthly income. Most conventional lenders want this to be 28% or less.
- Back-end ratio (total DTI) — all your monthly debt payments (housing + car loans + student loans + credit card minimums + other debts) divided by gross monthly income. Most conventional lenders allow up to 43–45%, though some programs go to 50%.
FHA loans are more flexible and may allow back-end DTI up to 50–57% with compensating factors like a large down payment or excellent credit.
A Practical Example
Let's say you earn $85,000 per year ($7,083/month gross). You have $400/month in car payments and $200/month in student loan payments — $600/month in existing debt obligations.
At a 43% back-end DTI limit:
- Maximum total monthly debt: $7,083 × 43% = $3,046
- Minus existing debts: $3,046 - $600 = $2,446 available for housing
With a $2,446 housing budget at 7% interest on a 30-year loan, plus taxes and insurance, you might qualify for a home priced around $310,000–340,000. This is the lender's ceiling — not necessarily your personal ceiling.
The 28% Rule: A Conservative Starting Point
A widely-used rule of thumb is to keep your total housing costs under 28% of your gross monthly income. This is more conservative than most lenders require, but it leaves breathing room for emergencies, savings, and lifestyle.
On a $7,083 gross monthly income:
- 28% = $1,983/month for all housing costs
- At 7% interest, 30 years, with taxes and insurance, this supports a home around $230,000–260,000
Notice the difference: lenders might approve you for $340,000, but a conservative budget puts you at $250,000. The extra $90,000 in home price would mean $400–500 more per month in housing costs — and significantly less money for retirement, emergencies, and everything else.
How Your Down Payment Affects What You Can Afford
A larger down payment reduces your loan amount, which lowers your monthly payment and may eliminate PMI. It also gives you more equity from day one, reducing the risk of being underwater if home prices dip.
The traditional 20% down payment has three major benefits:
- Eliminates PMI (saves $100–300/month)
- Lower monthly payment
- More competitive offers in bidding situations
However, many buyers purchase with less than 20% down through conventional loans (as low as 3% down), FHA loans (3.5% down), VA loans (0% for eligible veterans), or USDA loans (0% in eligible rural areas). The tradeoff is higher monthly costs due to PMI and a larger loan amount.
Down payment assistance programs are available in most states for first-time buyers. The National Council of State Housing Agencies (NCSHA) maintains a directory of programs at ncsha.org.
What Many Buyers Forget to Budget For
The purchase price is just the beginning. Before setting your home budget, make sure you've accounted for:
- Closing costs — typically 2%–5% of the purchase price, paid at closing (in addition to your down payment)
- Moving costs — $1,000–5,000 depending on distance and how much you're moving
- Immediate repairs and purchases — even move-in ready homes often need new appliances, window treatments, paint, or minor repairs
- Emergency fund — you should keep 3–6 months of expenses in savings after closing, not drain your savings to zero for the down payment
- Ongoing maintenance — budget 1%–2% of the home's value per year for repairs and maintenance
- HOA fees — if applicable, these can be $200–800/month in some communities
Your Credit Score's Impact on Affordability
Your credit score affects your mortgage interest rate, which directly affects how much house you can afford. The difference between a 680 and a 760 credit score can mean 0.5%–1.0% difference in interest rate — which on a $300,000 loan is $100–200 more per month, or the equivalent of $20,000–35,000 in purchasing power.
If your credit score is below 740, it may be worth spending 6–12 months improving it before applying for a mortgage. Pay down credit card balances, avoid opening new accounts, and dispute any errors on your credit report.
The "Comfortable" Affordability Test
Beyond the lender's numbers, ask yourself these questions:
- After paying all housing costs, can I still contribute 10–15% of income to retirement?
- After housing, do I have money left for childcare, healthcare, and other non-negotiable expenses?
- If one income earner lost their job, could we make the payment for 3–6 months while rebuilding?
- Am I buying this home because I genuinely want it and can afford it, or because I feel pressure to "get into the market"?
If you can't answer yes to all of these, the home may be at the outer edge of — or beyond — what's truly affordable for your situation.
Calculate Your Home Budget Instantly
Our free Home Affordability Calculator takes your income, monthly debts, down payment, and local interest rates to show you exactly what home price you can comfortably afford — based on both the 28% housing ratio and the 43% total DTI limit. It also shows how paying off debts or increasing your down payment expands your budget.
Key Takeaways
- Lender approval amount and comfortable affordability are two different numbers
- Keep total housing costs under 28%–36% of gross income for a sustainable budget
- Your down payment, credit score, and existing debts all affect how much you can borrow
- Budget for closing costs, moving costs, and reserves on top of the down payment
- Ask yourself the tough questions before committing to a payment level you'll struggle to maintain