Your Estimated Mortgage Affordability
Enter your details above to see your estimated maximum mortgage amount.
function calculateMortgageAffordability() {
var annualIncome = parseFloat(document.getElementById("annualIncome").value);
var existingDebts = parseFloat(document.getElementById("existingDebts").value);
var downPayment = parseFloat(document.getElementById("downPayment").value);
var interestRate = parseFloat(document.getElementById("interestRate").value);
var loanTerm = parseFloat(document.getElementById("loanTerm").value);
var resultDiv = document.getElementById("result");
resultDiv.innerHTML = ""; // Clear previous results
// Basic validation
if (isNaN(annualIncome) || isNaN(existingDebts) || isNaN(downPayment) || isNaN(interestRate) || isNaN(loanTerm) ||
annualIncome <= 0 || existingDebts < 0 || downPayment < 0 || interestRate <= 0 || loanTerm <= 0) {
resultDiv.innerHTML = "Please enter valid positive numbers for all fields.";
return;
}
// Lender Affordability Guidelines (Commonly used, but can vary)
// Guideline 1: Housing expenses (PITI – Principal, Interest, Taxes, Insurance) should not exceed 28% of gross monthly income.
// Guideline 2: Total debt obligations (including housing) should not exceed 36% of gross monthly income.
var grossMonthlyIncome = annualIncome / 12;
var maxMonthlyHousingPayment = grossMonthlyIncome * 0.28;
var maxTotalMonthlyObligations = grossMonthlyIncome * 0.36;
var maxMonthlyDebtService = maxTotalMonthlyObligations – existingDebts;
// Determine the lower of the two maximum monthly payments allowed
var maxMonthlyMortgagePayment = Math.min(maxMonthlyHousingPayment, maxMonthlyDebtService);
// If maxMonthlyMortgagePayment is negative, it means existing debts are too high relative to income.
if (maxMonthlyMortgagePayment 0 && numberOfPayments > 0) {
var factor = Math.pow(1 + monthlyInterestRate, numberOfPayments);
maxLoanAmount = maxMonthlyMortgagePayment * (factor – 1) / (monthlyInterestRate * factor);
} else if (monthlyInterestRate === 0 && numberOfPayments > 0) {
// Handle zero interest rate case (though rare for mortgages)
maxLoanAmount = maxMonthlyMortgagePayment * numberOfPayments;
}
var estimatedMaxMortgage = maxLoanAmount;
// Add back the down payment to get an estimated maximum home price
var estimatedMaxHomePrice = estimatedMaxMortgage + downPayment;
// Display the results
resultDiv.innerHTML =
"
Estimated Maximum Mortgage Amount: $" + estimatedMaxMortgage.toFixed(2) + "" +
"
Estimated Maximum Home Price (including down payment): $" + estimatedMaxHomePrice.toFixed(2) + "" +
"
Note: This is an estimate based on common lending guidelines (28% housing, 36% total debt ratio). Actual loan approval depends on lender's specific criteria, credit score, employment history, and other factors. Taxes, insurance, and HOA fees (PITI) are not fully factored into the housing ratio for simplicity.";
}
.calculator-wrapper {
font-family: sans-serif;
max-width: 700px;
margin: 20px auto;
padding: 20px;
border: 1px solid #ddd;
border-radius: 8px;
background-color: #f9f9f9;
display: flex;
flex-wrap: wrap;
gap: 20px;
}
.calculator-form, .calculator-result {
flex: 1;
min-width: 300px;
}
.calculator-form h2, .calculator-result h3 {
color: #333;
margin-bottom: 15px;
}
.calculator-form p {
color: #555;
line-height: 1.6;
margin-bottom: 20px;
}
.form-group {
margin-bottom: 15px;
}
.form-group label {
display: block;
margin-bottom: 5px;
font-weight: bold;
color: #444;
}
.form-group input[type="number"] {
width: calc(100% – 20px);
padding: 10px;
border: 1px solid #ccc;
border-radius: 4px;
font-size: 1rem;
}
.calculator-form button {
background-color: #007bff;
color: white;
padding: 12px 20px;
border: none;
border-radius: 4px;
cursor: pointer;
font-size: 1rem;
transition: background-color 0.3s ease;
}
.calculator-form button:hover {
background-color: #0056b3;
}
.calculator-result {
background-color: #fff;
padding: 15px;
border: 1px solid #eee;
border-radius: 4px;
}
.calculator-result p {
color: #333;
line-height: 1.6;
}
.calculator-result strong {
color: #007bff;
}
.calculator-result em {
font-size: 0.9em;
color: #666;
display: block;
margin-top: 10px;
}