On a $100,000 salary with no other debts and a 20% down payment, you can likely afford a home in the $350,000 to $420,000 range. With a smaller down payment or existing monthly debts like car payments and student loans, that number drops closer to $275,000 to $350,000. The exact figure depends on your interest rate, where you buy, and how much debt you’re already carrying.
How Lenders Decide What You Can Borrow
Lenders use a metric called your debt-to-income ratio (DTI) to determine how much mortgage you qualify for. DTI compares your total monthly debt payments to your gross monthly income, which is your pay before taxes. On a $100,000 salary, your gross monthly income is about $8,333.
There are two DTI numbers lenders look at. The front-end ratio covers only your housing costs: mortgage principal, interest, property taxes, and insurance. Most lenders want this at or below 28% of your gross income, which works out to roughly $2,333 per month on a $100k salary. The back-end ratio includes your housing costs plus all other monthly debts like car loans, student loans, and minimum credit card payments. Conventional loans underwritten through automated systems allow a back-end DTI up to 50%, though 43% to 45% is a more common approval threshold. Manually underwritten conventional loans cap at 36%, or up to 45% with strong credit and cash reserves.
What Your Monthly Payment Actually Includes
Your mortgage payment isn’t just principal and interest. Lenders qualify you based on the full monthly housing cost, often called PITI: principal, interest, taxes, and insurance. Here’s what each piece looks like for a typical purchase.
- Principal and interest: At a 6.23% rate on a 30-year fixed mortgage (roughly where rates sit as of spring 2025), you’ll pay about $6.15 per month for every $1,000 borrowed. A $300,000 loan comes to approximately $1,845 per month in principal and interest alone.
- Property taxes: These vary widely by location but average around 1% of a home’s value per year. On a $350,000 home, that’s about $292 per month.
- Homeowners insurance: The national average runs about $2,424 per year for a policy with $300,000 in dwelling coverage, or roughly $202 per month. Costs swing dramatically by location, from under $70 per month in lower-cost areas to over $500 in high-risk regions.
- Private mortgage insurance (PMI): If you put down less than 20%, you’ll pay PMI, which typically costs $30 to $70 per month for every $100,000 borrowed. On a $300,000 loan, that adds $90 to $210 per month.
Most lenders collect your tax and insurance payments as part of your monthly bill through an escrow account, so you’ll see one combined payment each month rather than paying each item separately.
Sample Budgets at $100,000 Income
These examples assume a 6.23% rate on a 30-year fixed mortgage, average property taxes around 1%, and typical insurance costs. Your local numbers may shift the math in either direction.
$370,000 Home With 20% Down
A 20% down payment means putting $74,000 down and borrowing $296,000. Your monthly principal and interest would be about $1,821. Add roughly $308 for property taxes and $225 for insurance, and your total housing payment lands near $2,354 per month. That’s just about 28% of your gross income and avoids PMI entirely. This scenario works well if you have no other significant debts.
$320,000 Home With 10% Down
Putting 10% down ($32,000) means borrowing $288,000. Principal and interest come to roughly $1,771. Property taxes add about $267, insurance around $210, and PMI roughly $120 to $170 per month. Your total housing payment falls between $2,368 and $2,418. That’s right at the 28% to 29% front-end limit, leaving less breathing room if you carry other debts.
$275,000 Home With 5% Down
At 5% down ($13,750), you borrow $261,250. Principal and interest run about $1,607. Add $229 for taxes, $190 for insurance, and $130 to $180 for PMI, and you’re looking at roughly $2,156 to $2,206 per month. This keeps your front-end ratio around 26%, which gives you more room for existing debts in the back-end calculation.
How Existing Debts Shrink Your Budget
Every dollar you owe in monthly payments reduces how much mortgage you can qualify for. If you’re paying $400 per month on a car loan and $300 per month toward student loans, that’s $700 per month that counts against your back-end DTI.
Using a 43% back-end limit, your total allowable monthly debt is about $3,583. Subtract $700 in existing obligations, and you have $2,883 left for housing. That still supports a solid mortgage, but if your debts are closer to $1,200 or $1,500 per month, your housing budget tightens to $2,000 or less, which could push your affordable purchase price below $300,000.
Paying off a car loan or credit card balance before applying doesn’t just free up room in your DTI. It can also improve your credit score, which may get you a better interest rate. Even a quarter-point rate difference on a $300,000 loan changes your monthly payment by about $50 and saves over $17,000 in interest over 30 years.
Why the 28% Rule Is a Starting Point
The 28% guideline tells you what lenders will approve, not necessarily what’s comfortable. Your gross income of $8,333 per month drops significantly after federal and state income taxes, retirement contributions, and health insurance premiums. Depending on your tax situation, your take-home pay on $100,000 might be closer to $5,800 to $6,500 per month.
A $2,300 housing payment that looks reasonable against your gross income could eat up 35% to 40% of your actual take-home pay. If you also want to save for retirement, build an emergency fund, and cover childcare or other major expenses, you might feel more comfortable targeting 25% of gross income or even less. That would put your housing payment closer to $2,083, which supports a purchase price in the $300,000 to $350,000 range with 20% down.
Factors That Push Your Number Up or Down
Interest rates have the single biggest impact on affordability. At 5.5%, a $300,000 loan costs $1,703 per month in principal and interest. At 7%, the same loan costs $1,996. That $293 difference either lets you afford a more expensive home or forces you to shop lower. Locking in a rate when the market dips even slightly can meaningfully expand your budget.
Your credit score directly affects the rate you’re offered. Borrowers with scores above 740 generally receive the best rates, while scores in the low 600s may see rates a full percentage point or more higher. On a $300,000 loan, that gap translates to roughly $200 extra per month.
Property taxes and insurance vary enough by location to shift your affordable price by $50,000 or more. A home in a low-tax area with cheap insurance leaves more of your $2,333 monthly budget for the actual mortgage, letting you buy a pricier home. A home in a high-tax, high-insurance area eats into that budget fast. When you’re shopping, ask about the actual tax bill on any home you’re considering rather than relying on national averages.
Getting a Realistic Number Before You Shop
The quickest way to pin down your personal number is to get preapproved by a lender. Preapproval involves a credit check and income verification, and the lender will tell you exactly how much they’re willing to lend based on your full financial picture. The process typically takes a few days and is free.
Before you reach that step, you can estimate your own affordability by adding up all your current monthly debt payments, subtracting that from 43% of your gross monthly income ($3,583), and treating whatever’s left as your maximum housing budget. Then back into a home price using current rates and your expected down payment. If the resulting number feels tight against your actual take-home pay, trust that instinct and shop below your maximum.