Please enter valid numbers for income and interest rate.
You Can Afford a House Worth:
$0
Loan Amount:$0
Monthly Principal & Interest:$0
Monthly Taxes & Insurance:$0
Total Monthly Payment:$0
Debt-to-Income Used:0%
How Much House Can You Really Afford?
Understanding your purchasing power is the first step in the home buying journey. This Mortgage Affordability Calculator uses the same "Debt-to-Income" (DTI) ratios that lenders use to determine your eligibility for a loan. By analyzing your income, current debts, and down payment savings, we calculate a realistic home price budget that fits your financial profile.
How This Calculator Works
Lenders typically look at two primary ratios to decide how much they will lend you:
Front-End Ratio (28%): Typically, your housing costs (mortgage principal, interest, taxes, and insurance) should not exceed 28% of your gross monthly income.
Back-End Ratio (36%): Your total monthly debt payments (housing costs + credit cards + car loans + student loans) should not exceed 36% of your gross monthly income.
Our calculator computes both scenarios and uses the lower number to ensure you stay within a safe financial limit, preventing you from becoming "house poor."
Key Factors Affecting Affordability
1. Down Payment: A larger down payment reduces the loan amount needed, lowering your monthly payments and potentially allowing you to purchase a more expensive home.
2. Interest Rates: Even a small difference in interest rates can significantly impact your buying power. As rates rise, the maximum home price you can afford decreases because more of your monthly payment goes toward interest.
3. Monthly Debts: High monthly obligations (like an expensive car payment) directly reduce the amount of income available for a mortgage. Paying down aggressive debts can boost your affordability significantly.
Frequently Asked Questions
What is included in "Monthly Debts"?
Include minimum monthly payments for credit cards, student loans, auto loans, alimony, and child support. Do not include utility bills or grocery costs.
Does this include PMI?
If your down payment is less than 20%, lenders usually require Private Mortgage Insurance (PMI). While this calculator estimates taxes and insurance, be aware that PMI can add 0.5% to 1% of the loan amount annually to your costs.
function calculateAffordability() {
// Get Input Values
var annualIncome = parseFloat(document.getElementById('annualIncome').value);
var monthlyDebts = parseFloat(document.getElementById('monthlyDebts').value) || 0;
var downPayment = parseFloat(document.getElementById('downPayment').value) || 0;
var interestRate = parseFloat(document.getElementById('interestRate').value);
var loanTermYears = parseInt(document.getElementById('loanTerm').value);
var propTaxRate = parseFloat(document.getElementById('propTax').value) || 0;
var homeInsuranceYearly = parseFloat(document.getElementById('homeInsurance').value) || 0;
// Error Handling
var errorDiv = document.getElementById('errorMsg');
if (isNaN(annualIncome) || isNaN(interestRate) || annualIncome <= 0) {
errorDiv.style.display = 'block';
document.getElementById('resultsSection').style.display = 'none';
return;
}
errorDiv.style.display = 'none';
// 1. Calculate Monthly Income
var monthlyIncome = annualIncome / 12;
// 2. Define Limits (Standard Conventional Loan Ratios)
// Front-End Ratio: Housing <= 28% of Income
var limitFront = monthlyIncome * 0.28;
// Back-End Ratio: Total Debts <= 36% of Income
// Max Housing = (Income * 0.36) – Other Debts
var limitBack = (monthlyIncome * 0.36) – monthlyDebts;
// If debts are too high, limitBack could be negative, meaning affordabilty is 0
if (limitBack 0) {
loanAmount = numerator / denominator;
} else {
// Costs (Insurance/Tax on downpayment) exceed max payment
loanAmount = 0;
}
var maxHomePrice = loanAmount + downPayment;
// 4. Calculate Result breakdowns based on the derived Home Price
var monthlyPropTax = maxHomePrice * tFactor;
var monthlyPandI = loanAmount * mFactor;
var totalMonthly = monthlyPandI + monthlyPropTax + iMonth;
// 5. Update UI
document.getElementById('maxHomePrice').innerText = formatCurrency(maxHomePrice);
document.getElementById('resLoanAmount').innerText = formatCurrency(loanAmount);
document.getElementById('resPandI').innerText = formatCurrency(monthlyPandI);
document.getElementById('resTaxIns').innerText = formatCurrency(monthlyPropTax + iMonth);
document.getElementById('resTotalMonthly').innerText = formatCurrency(totalMonthly);
document.getElementById('resDTI').innerText = usedDTI;
document.getElementById('resultsSection').style.display = 'block';
}
function formatCurrency(num) {
return '$' + num.toFixed(0).replace(/(\d)(?=(\d{3})+(?!\d))/g, '$1,');
}