Home Affordability Calculator

What “home affordability” really means

“How much house can I afford?” sounds like one number, but it’s really a trade‑off between your monthly payment comfort zone and the market realities of interest rates, property taxes, and insurance. Lenders often use ratios (like DTI) to decide what you can qualify for, but you should also stress‑test whether the payment still works for your lifestyle.

A helpful way to use this calculator is to run 2-3 scenarios: a conservative payment, a baseline payment, and a stretch payment. The “right” answer is the one that leaves you room for real life.

How this home affordability calculator works

This tool estimates the largest home price that fits inside two common limits:

• Max DTI (debt-to-income): total monthly debt payments (including housing) as a percent of gross monthly income.
• Max housing ratio: housing payment alone as a percent of gross monthly income.

We calculate your maximum monthly housing payment using both limits and take the lower (more restrictive) result. Then we subtract non‑mortgage housing costs (taxes, insurance, HOA, and optional PMI) to get the maximum principal‑and‑interest (P&I) payment. Finally, we convert that P&I payment into an estimated loan amount using standard amortization math.

DTI vs housing ratio: why both matter

The housing ratio is a quick “front‑end” check: if your mortgage payment is too large compared to income, the budget gets tight fast. DTI is a “back‑end” check that includes everything else you owe each month, like car payments, student loans, and minimum credit card payments.

Step-by-step: getting a solid estimate

A simple process that avoids the most common mistakes:

1. Start with your gross annual income (before taxes) and realistic monthly debt payments.
2. Use today’s best guess for interest rate and term (30‑year fixed is a common baseline).
3. Enter property tax and insurance as annual totals, if you’re unsure, estimate high rather than low.
4. Try two down payments (example: 10% vs 20%) and watch how it changes PMI and the loan size.
5. When you have a price range, verify the payment using the Mortgage Calculator and compare renting with the Rent vs Buy Calculator.

For a broader overview of all tools on the site, visit our calculators hub.

Choosing assumptions (and what this calculator doesn’t include)

This page focuses on the big levers that change affordability the most. But real home buying includes other costs and rules. Here are a few that can swing the result:

• Closing costs: often several percent of the purchase price (loan fees, escrow, title, etc.).
• Rate changes: even a 0.5% shift can meaningfully change the maximum loan amount.
• PMI specifics: PMI depends on down payment, credit, and loan type, use your lender quote when possible.
• Maintenance and utilities: not part of “qualifying ratios,” but absolutely part of affordability.

Common mistakes (and how to avoid them)

The biggest mistake is treating the maximum as the target. Instead, treat this result as a ceiling and pick a payment that feels comfortable even on a bad month. A close second is forgetting that property taxes and insurance can be large, and may rise over time.

If your result looks too low, look first at monthly debts and interest rate. Reducing debt payments can increase affordability because it frees up DTI capacity. If the result looks too high, lower the housing ratio and add a conservative PMI estimate to reflect a smaller down payment.

A quick example you can copy

Suppose you earn $120,000 per year, have $650 per month in other debt payments, and want to keep housing around 28% of gross income. Your gross monthly income is $10,000, so a 28% housing ratio suggests a maximum housing payment around $2,800/month. If your DTI limit is 36%, the DTI-based maximum would be $3,600 − $650 = $2,950/month. In this example, the housing ratio is the limiting factor.

Now subtract “extras” like property taxes and insurance. If taxes are $6,500/year and insurance is $1,800/year, that’s about $692/month in extras (before HOA/PMI). That leaves about $2,108/month for principal-and-interest (P&I). With a 30‑year loan, a higher rate can shrink the loan amount fast, so it’s worth testing a couple of rate values if you’re shopping in a volatile market.

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