Updated · Methodology: named formula library
House Affordability Calculator
Determine how much house you can afford based on income, debts, and down payment.
Your estimated monthly mortgage payment is $1,871 for a $300,000 loan at 6.4% over 30 years.
Why This Calculation Matters
The House Affordability Calculator helps you make better real estate decisions by putting the math directly in front of you. Instead of relying on averages or guesswork, plug in your own numbers and see how the key inputs, rate, term, amount, and timing, interact. Small changes to any one of them can have outsized effects over years or decades.
How to Use This Calculator
- Enter your values in the input fields, each one has a label and help text explaining what to type.
- Results appear instantly as you type; there's no "calculate" button to press.
- Change any input to compare scenarios side by side.
All math happens in your browser. Nothing you type is sent to a server, saved, or shared.
Key Inputs to Get Right
The most important numbers are usually the interest rate and the time horizon. Over years or decades, small rate differences compound into large dollar differences, so it's worth sanity-checking the rate against current market data before acting on any result.
How to Use the House Affordability Calculator
Enter the required values in the input fields on the left. Results update instantly on the right as you adjust your inputs.
Understanding Your Results
Review each output value and its description to understand how your inputs affect the outcome. Adjust values to compare different scenarios.
Tips
- All calculations happen in your browser, your data is never stored
- Bookmark this page for quick access
- Try different values to see how results change
Formula
The 28/36 rule: housing expenses ≤ 28% of gross monthly income, total debt ≤ 36%. Some lenders allow up to 43% debt-to-income (DTI) for a qualified mortgage.
Worked Example
$300k loan at 7% over 30 years
- principal
- 300000
- rate
- 7
- years
- 30
- Result
- $1,995.91/month
Monthly principal + interest. Total paid: $718,526.69.
When to Use This Calculator
- Model scenarios before making a major financial decision involving real estate.
- Compare different inputs side by side to see how rate, term, or amount changes your outcome.
- Sanity-check numbers a lender, advisor, or spreadsheet has given you.
- Build a realistic financial plan grounded in your actual numbers, not averages.
Limitations & Common Mistakes
- Results are estimates, actual terms depend on credit, lender policy, taxes, and fees not captured here.
- Rates and prices change daily; recompute with current numbers before signing documents.
- Does not constitute financial advice. For major decisions, consult a licensed advisor.
Frequently Asked Questions
How does the House Affordability Calculator work?
Enter your loan amount (default: 300000) and any other inputs; the calculator instantly applies its house affordability formula and shows the result with details. All math runs in your browser; nothing is sent to a server.
Is the House Affordability Calculator accurate for real estate decisions?
It uses standard, documented formulas that match published references. For high-stakes real estate decisions, verify the result against an authoritative source (industry calculator, professional advisor, or government data). The calculator is a planning estimate, not a substitute for professional judgment.
What inputs does the House Affordability Calculator require?
3 inputs: Loan Amount, Interest Rate, Loan Term (years). Each has a sensible default; replace with your own values to get a result tailored to your situation.
Can I bookmark or share the House Affordability Calculator?
Yes — the URL is stable: https://www.calcintel.com/calculator/house-affordability. Inputs reset to defaults on each visit (no input is stored), so screenshot or copy the result if you want to preserve a specific scenario.
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Related guides
- Reading Your Paycheck: What Every Deduction Actually Means in 2026Federal income tax, FICA, Medicare surtax, state tax, 401(k), HSA, FSA, health premiums, garnishments, line by line, with the exact 2026 rates and thresholds applied to real sample paychecks.
- Compound Interest, Explained in the Math Your Calculator Actually UsesThe formula A = P(1 + r/n)^(nt) is one of the most useful equations in personal finance. Here is how each variable actually behaves, and why compounding frequency matters less than you think.
- Why the 28/36 Rule Fails Most Homebuyers in 2025The classic mortgage-affordability rule was built for a world without student loans, rising property taxes, or $8,000 HOA dues. Here is a better framework, and the DTI math lenders actually use.
Source: BLS Consumer Price Index, 2026.