Uses standard front-end and back-end debt-to-income guidelines — adjust the sliders to match your lender's actual limits. Doesn't account for PMI, closing costs, or credit score, all of which affect real approval. This is not a loan pre-approval.
What is a mortgage affordability calculator?
A mortgage affordability calculator answers "how much house can I afford" by working backwards from the debt-to-income limits lenders apply, rather than forwards from a price you picked.
It takes your income, your existing monthly debts, and your down payment, then finds the largest home price whose full monthly cost — principal, interest, property tax, insurance and HOA — still fits inside those limits. The conventional guidelines are 28% of gross income on housing and 36% on total debt, both adjustable here.
Worth saying plainly: this shows what you'd likely be approved for. What you can comfortably afford is often a smaller number.
How lenders decide what you can borrow
Affordability is governed by two debt-to-income ratios. This calculator solves backwards from those limits to find your maximum home price.
Front-end ratio
Your total housing payment — principal, interest, taxes, insurance, HOA — divided by gross monthly income. Commonly capped near 28%.
Back-end ratio
Housing plus all other monthly debt: car loans, student loans, credit card minimums. Commonly capped near 36%.
The lower limit wins
Whichever ratio binds first sets your budget. With significant existing debt, the back-end ratio is usually the constraint.
What that looks like with real numbers
$95,000 household income, $400 in other monthly debts, $40,000 down, 6.5% for 30 years:
Here the 28% front-end rule binds first ($2,217) rather than the back-end ($2,450). Clearing that $400 of other debt wouldn't raise the budget at all — but a lower rate would.
Rate sensitivity is brutal
At a fixed monthly budget, each percentage point of interest rate moves your buying power roughly 10%. The same $2,217/month buys meaningfully more house at 5.5% than at 7.5%. This is why affordability shifts so sharply when rates move, even when prices don't.
The maximum a lender approves is not a recommendation. Approval is based on your ability to service debt, not on leaving room for retirement saving, childcare, home repairs, or a job loss. Many buyers deliberately target well below their ceiling.
Costs this calculator doesn't include
PMI (private mortgage insurance)
If your down payment is under 20%, expect to pay roughly 0.3–1.5% of the loan annually until you build sufficient equity. On a $284,000 loan that's often $70–$350 per month on top of everything shown here.
Closing costs
Typically 2–5% of the purchase price, due at signing and separate from your down payment. On a $324,000 home that's roughly $6,500–$16,000 that needs to exist in cash.
Maintenance and the rest
A common planning figure is 1% of home value per year for upkeep — about $270/month on this example, and it doesn't appear on any mortgage statement. Utilities usually rise when moving from renting too.
Your credit score
It doesn't change these ratios, but it heavily influences the rate you're offered — and as shown above, the rate drives your budget. Improving a score before applying can be worth more than saving another few thousand for the down payment.
Common questions
The things people usually want to know before trusting a number like this.
Where do 28% and 36% come from?
They're long-standing conventional underwriting guidelines. Real limits vary by loan program and lender: FHA loans often permit higher ratios, and strong compensating factors like large reserves or excellent credit can stretch them. Both sliders are adjustable so you can model your actual lender's limits.
Should I really borrow the maximum?
Usually not. The ratios say nothing about your other goals or your risk tolerance. A payment at your absolute ceiling leaves no margin for a rate reset, a job change, or a roof replacement. Plenty of financially comfortable people deliberately buy at 60–70% of what they were approved for.
Does a bigger down payment increase my budget?
Yes, in two ways. It directly adds to the price you can reach at the same monthly payment, and crossing 20% removes PMI, which frees up more monthly room. It also typically improves the rate offered. The trade-off is liquidity — draining savings entirely to reach 20% carries its own risk.
How accurate is the property tax estimate?
It's a straight percentage of home value, which approximates how most US jurisdictions assess. Actual rates vary widely by county — under 0.5% in some states, above 2% in others — and some areas add special assessments. Look up your target county's effective rate and enter it for a realistic figure.
Is this a pre-approval?
No. A real pre-approval involves a credit pull, income and asset verification, and a lender's own underwriting. Use this to narrow your search range before talking to lenders, not as evidence of what you can borrow.
Guides on buying a home
Plain-English explanations of the concepts behind this calculator.
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