Your Estimated Maximum Mortgage Amount
Enter your details above to see your estimated maximum mortgage affordability.
.calculator-wrapper {
font-family: sans-serif;
max-width: 600px;
margin: 20px auto;
padding: 20px;
border: 1px solid #ddd;
border-radius: 8px;
background-color: #f9f9f9;
display: flex;
flex-wrap: wrap;
gap: 30px;
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.calculator-inputs {
flex: 1;
min-width: 250px;
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.calculator-results {
flex: 1;
min-width: 250px;
background-color: #fff;
padding: 15px;
border-radius: 5px;
border: 1px solid #eee;
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.input-group {
margin-bottom: 15px;
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.input-group label {
display: block;
margin-bottom: 5px;
font-weight: bold;
color: #333;
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.input-group input[type="number"] {
width: calc(100% – 12px);
padding: 8px;
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border-radius: 4px;
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button {
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color: white;
padding: 10px 15px;
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button:hover {
background-color: #0056b3;
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#result p {
font-size: 1.2em;
color: #007bff;
font-weight: bold;
margin: 0;
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#result span {
font-size: 1.5em;
color: #28a745;
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var calculateMortgageAffordability = function() {
var annualIncome = parseFloat(document.getElementById("annualIncome").value);
var monthlyDebt = parseFloat(document.getElementById("monthlyDebt").value);
var downPayment = parseFloat(document.getElementById("downPayment").value);
var annualInterestRate = parseFloat(document.getElementById("interestRate").value) / 100;
var loanTermYears = parseInt(document.getElementById("loanTerm").value);
var resultDiv = document.getElementById("result");
resultDiv.innerHTML = "; // Clear previous results
// Basic validation
if (isNaN(annualIncome) || isNaN(monthlyDebt) || isNaN(downPayment) || isNaN(annualInterestRate) || isNaN(loanTermYears)) {
resultDiv.innerHTML = 'Please enter valid numbers for all fields.';
return;
}
// Standard Debt-to-Income (DTI) ratios. Lenders often use 36% for front-end (housing) and 43% for back-end (total debt).
// We'll use a common guideline where total monthly housing costs (PITI) should not exceed ~28% of gross monthly income
// and total debt (including housing) should not exceed ~36-43% of gross monthly income.
// For affordability, we'll focus on the 'housing' portion first, and then ensure total debt is within limits.
var grossMonthlyIncome = annualIncome / 12;
// Assumption: Max housing payment (PITI) is ~28% of gross monthly income.
var maxMonthlyHousingPayment = grossMonthlyIncome * 0.28;
// Assumption: Total debt payments (including estimated mortgage P&I) should not exceed ~36% of gross monthly income.
// This means the mortgage P&I part of PITI needs to be calculated considering the monthly debt already exists.
var maxTotalMonthlyDebtAllowed = grossMonthlyIncome * 0.36;
var maxMonthlyPrincipalInterest = maxTotalMonthlyDebtAllowed – monthlyDebt;
// We'll take the more conservative of the two estimations for monthly P&I affordability
var affordableMonthlyPI = Math.min(maxMonthlyHousingPayment, maxMonthlyPrincipalInterest);
if (affordableMonthlyPI 0 && numberOfPayments > 0) {
var numerator = Math.pow((1 + monthlyInterestRate), numberOfPayments) – 1;
var denominator = monthlyInterestRate * Math.pow((1 + monthlyInterestRate), numberOfPayments);
principalLoanAmount = affordableMonthlyPI * (numerator / denominator);
} else if (affordableMonthlyPI > 0) { // Case for 0% interest or 0 term (though unlikely for mortgages)
principalLoanAmount = affordableMonthlyPI * numberOfPayments;
}
var maxMortgageAmount = principalLoanAmount + downPayment;
// Display the result
resultDiv.innerHTML = 'Estimated Maximum Mortgage Amount:
$' + maxMortgageAmount.toLocaleString(undefined, { maximumFractionDigits: 0 }) + '';
};
Understanding Mortgage Affordability
Determining how much you can afford for a mortgage is a crucial step in the home-buying process. It's not just about what a lender is willing to give you; it's about what you can comfortably manage each month without straining your finances. This calculator helps you estimate your maximum mortgage affordability based on your income, existing debts, and down payment.
Key Factors in Mortgage Affordability:
- Gross Monthly Income: This is your total income before taxes and deductions. Lenders look at your household's combined income to assess your ability to repay the loan.
- Monthly Debt Payments: This includes all your recurring monthly financial obligations other than your potential mortgage payment. Common examples are car loans, student loans, credit card minimum payments, and personal loans. High existing debt can significantly reduce how much mortgage you can afford.
- Down Payment: The upfront cash you pay towards the home purchase. A larger down payment reduces the loan amount needed, making the mortgage more affordable and potentially leading to better interest rates and avoiding Private Mortgage Insurance (PMI) if it's 20% or more of the home's purchase price.
- Interest Rate: The percentage charged by the lender for borrowing money. Even a small difference in interest rates can significantly impact your monthly payment and the total interest paid over the life of the loan.
- Loan Term: The length of time you have to repay the mortgage, typically 15 or 30 years. Shorter terms have higher monthly payments but result in less interest paid overall.
How the Calculator Works (Simplified):
This calculator uses common lending guidelines to estimate affordability. It generally assumes:
- Front-End Ratio (Housing Expense Ratio): Your total monthly housing costs (Principal, Interest, Taxes, and Insurance – PITI) should ideally not exceed 28% of your gross monthly income.
- Back-End Ratio (Debt-to-Income Ratio): Your total monthly debt obligations (including the estimated mortgage PITI) should not exceed 36% to 43% of your gross monthly income.
The calculator first determines the maximum monthly housing payment you can afford based on your income and then factors in your existing debts to see how much is left for the mortgage principal and interest (P&I). It then calculates the maximum loan amount you can borrow based on that affordable P&I payment, interest rate, and loan term. Finally, it adds your down payment to estimate the total home price you might be able to afford.
Important Considerations:
This calculator provides an estimate. Actual loan approval depends on many other factors, including your credit score, employment history, assets, lender-specific policies, and the specific costs of the home (property taxes, homeowner's insurance, potential HOA fees, and PMI if applicable). It's always best to get pre-approved by a mortgage lender for a precise understanding of your borrowing power.