Formulas and 2026 figures checked & updated: July 2026
Monthly gross: $7,917
Car loans, student loans, minimum credit card payments, etc.
How to Use the Home Affordability Calculator
- Enter your gross annual income — the calculator automatically converts it to a monthly figure.
- Add your existing monthly debt payments — credit cards, auto loans, and student loans.
- Enter your planned down payment amount.
- Enter the interest rate you expect to qualify for and choose your loan term (15, 20, or 30 years).
- Add estimated annual property tax and homeowners insurance so the result reflects a realistic full monthly payment.
- Review your maximum home price alongside the 28% and 36% DTI limits to see which one is more restrictive for your situation.
- Compare the result to your target market and adjust income, debt, or down payment assumptions as needed. Example: $120,000 income, $500/month in existing debts, and $60,000 down supports a maximum home price of roughly $409,000 at 6.875% over 30 years, after accounting for taxes and insurance.
What This Calculator Does
The Home Affordability Calculator estimates the maximum home price you can comfortably afford based on your gross income, existing monthly debts, planned down payment, expected interest rate, and loan term. Rather than starting from a home price and checking whether you qualify, it works backward from your income and debts to show the ceiling lenders are likely to approve — the number most house hunters need before they start touring homes or requesting a mortgage pre-approval.
The result is driven primarily by two debt-to-income (DTI) limits: the 28% front-end ratio, which caps your housing payment (principal, interest, taxes, and insurance) at 28% of gross monthly income, and the 36% back-end ratio, which caps all monthly debt — housing plus car loans, student loans, and credit card minimums — at 36% of gross income. These are the guidelines most conventional lenders apply, though FHA and some automated-underwriting programs allow back-end ratios up to 43-50% for well-qualified borrowers. A larger down payment also directly increases affordability: it shrinks the loan amount, lowers the required principal-and-interest payment, and — once you reach 20% down — eliminates PMI, freeing up more of your DTI budget for the home itself.
Homebuyers use this calculator early in the house-hunting process, before submitting a mortgage pre-approval application, to set a realistic price range and avoid falling for homes outside their budget. It's also useful for stress-testing 'what-if' scenarios — seeing how paying off a car loan, saving a larger down payment, or a change in interest rates shifts your maximum home price — so you can time a purchase around your actual finances rather than a lender's first estimate.
Formula
Max Housing Payment = min(0.28 × Gross Monthly Income, 0.36 × Gross Monthly Income − Other Debts)The lower of the two limits sets your maximum monthly housing payment. The calculator then subtracts estimated taxes, insurance, and PMI to find the portion available for principal & interest, and works backward through the mortgage formula to estimate your maximum loan — and home price.
- 28%Front-end ratio cap — housing costs ÷ gross monthly income
- 36%Back-end ratio cap — all debt payments ÷ gross monthly income
- Other DebtsCar loans, student loans, credit card minimums, etc.
Examples
Example 1: $95,000 income, $400 in monthly debts
Gross monthly income ≈ $7,917. 28% cap = $2,217/mo housing; 36% cap = $2,850 − $400 = $2,450/mo. The lower cap ($2,217) applies.
With $60,000 down at 6.875% over 30 years, this supports a maximum loan of about $260,000 — a home price of roughly $320,000 after taxes and insurance.
Example 2: Same income, but $800/mo in car & student loan payments
28% cap stays at $2,217/mo, but 36% cap drops to $2,850 − $800 = $2,050/mo — now the more restrictive limit.
Maximum affordable home price falls to roughly $295,000 — about $25,000 less than Example 1 — showing how existing debt directly shrinks buying power even though income didn't change.
Example 3: $150,000 income, no other debts, $100,000 down
Gross monthly income ≈ $12,500. 28% cap = $3,500/mo housing; 36% cap = $4,500/mo since there's no other debt. The 28% front-end cap applies.
With $100,000 down at 6.875% over 30 years, this supports a home price of roughly $555,000 — over 70% more buying power than Example 1, driven by higher income and zero other monthly debt.
Key Terms Explained
- Debt-to-Income (DTI)
- Your monthly debt payments divided by gross monthly income. Lenders typically want a back-end DTI of 36% or less, with 43% a common ceiling.
- Down Payment
- The upfront cash you pay toward a purchase, reducing the amount financed. A larger down payment lowers monthly payments and can avoid PMI.
- PMI (Private Mortgage Insurance)
- Insurance that protects the lender when a borrower puts down less than 20%. It's added to the monthly payment and drops off near 20–22% equity.
- Interest Rate
- The percentage a lender charges on the principal, before fees. Unlike APR, the interest rate alone doesn't include origination or other loan costs.
- Escrow
- An account your lender uses to collect and pay property taxes and homeowners insurance on your behalf, bundled into the monthly payment.
- Closing Costs
- One-time fees to finalize a mortgage (appraisal, title, origination, etc.), typically 2–5% of the loan amount.
Methodology
Uses the standard 28/36 debt-to-income guideline. Front-end ratio: housing costs (principal, interest, taxes, and insurance) must not exceed 28% of gross monthly income. Back-end ratio: total monthly debts, including the new mortgage, must not exceed 36%. The calculator applies the more restrictive of the two limits, subtracts estimated monthly taxes and insurance to isolate the principal-and-interest budget, then solves the standard amortization formula backward for the maximum loan amount, and adds your down payment to get the maximum home price.
Frequently Asked Questions
What is the 28/36 rule?+
The 28/36 rule is a widely-used debt-to-income guideline. It says your housing costs (mortgage, taxes, insurance) should not exceed 28% of gross monthly income, and your total monthly debts (housing + car loans + student loans + credit cards) should not exceed 36%. Most conventional lenders use this as a baseline.
Do I need 20% down to buy a home?+
No — many programs allow less. Conventional loans allow 3–5% down. FHA loans allow 3.5% with a 580+ credit score. VA loans allow 0% down for veterans. USDA loans allow 0% down in eligible rural areas. However, less than 20% down typically requires PMI, which adds to your monthly payment.
How does my credit score affect affordability?+
Your credit score directly affects your interest rate. Moving from a 680 to a 760 score could reduce your rate by 0.5–1%, saving thousands over the loan life. The difference between a 6.5% and 7.5% rate on a $350K loan is about $224/month — or $80,640 over 30 years.
How does PMI affect how much house I can afford?+
Private mortgage insurance (PMI) is required on conventional loans with less than 20% down, and it counts toward your 28% front-end DTI limit just like principal, interest, taxes, and insurance. PMI typically costs 0.5%-1.5% of the loan amount per year, so factoring it in reduces the housing budget left for principal and interest — and therefore your maximum home price — compared to a scenario with 20% down and no PMI.
Does my current rent count toward my debt-to-income ratio?+
No. Current rent isn't counted as a debt in the DTI calculation because it disappears once you buy a home and start making mortgage payments instead. Lenders only count ongoing obligations that continue after closing, such as auto loans, student loans, personal loans, and minimum credit card payments.
Can I qualify for a higher back-end DTI than 36%?+
Yes. Many loan programs allow higher back-end ratios for well-qualified borrowers — FHA loans often allow up to 43-50%, and some conventional loans with strong credit and cash reserves allow up to 45% or higher under automated underwriting. A higher DTI approval increases your borrowing power but also increases your monthly obligation, so it's worth treating the more conservative 36% figure as a safety cushion even if you qualify for more.
Can I save my results?+
Yes. Use “Save results” to store a snapshot. Without an account it remains in this browser. If you log in, saved scenarios sync securely to your SmartRates account so they are available on your other devices.
How do I share my calculation?+
Click “Share” in the toolbar to copy a link (or open your device’s share sheet). The link encodes your exact inputs, so whoever opens it sees the calculator pre-filled with the same numbers and the same result.
Can I email my calculator results?+
Yes. Click “Email results” to open your default email application with the current inputs, results, and calculator link already included. Review the message and choose the recipient before sending.
Can I export or print my results as a PDF?+
Yes. Click “Export PDF” to open a clean, printable summary of your inputs and results that you can save as a PDF or print. It includes a timestamp and a link back to the calculator.
How accurate are the calculator results?+
The arithmetic follows the formula and assumptions documented on this page. The result is still an estimate because actual rates, fees, taxes, timing conventions, eligibility rules, and provider calculations can differ. Use figures from your official quote, statement, contract, or tax form before making a financial decision.
Which inputs have the biggest effect on the result?+
Rate, time, starting balance, recurring payments or contributions, and fees usually have the largest effects. Change one input at a time to create a conservative, expected, and optimistic scenario instead of relying on a single forecast.
Are taxes, fees, and inflation included?+
Only when they appear as an input or are explicitly described in the methodology. Do not assume an omitted cost is zero. Review the formula and methodology sections to see exactly what is included before comparing the result with an outside quote.
Can this calculator predict future rates or returns?+
No. A calculator projects the assumptions entered; it cannot predict market returns, inflation, variable interest rates, tax-law changes, or provider decisions. Rerun the calculation with several assumptions to understand the range of possible outcomes.
Why might my lender, bank, broker, or tax software show a different result?+
Professional systems may use daily timing, transaction dates, compounding conventions, rounding rules, account-specific fees, credits, eligibility details, or regulations that a general-purpose calculator cannot know. A small difference can be rounding; a large difference usually means an assumption or included cost is different.
Disclaimer: Calculations are for informational purposes only and do not constitute professional financial advice. Please consult with a certified professional before making financial decisions.