Understanding how much house you can afford is a crucial first step in the home-buying process. This mortgage affordability calculator helps you estimate your potential borrowing power based on your income, debts, and down payment. Use these estimates as a guideline, and remember to consult with a mortgage professional for personalized advice.
function calculateAffordability() {
var annualIncome = parseFloat(document.getElementById("annualIncome").value);
var monthlyDebt = parseFloat(document.getElementById("monthlyDebt").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(monthlyDebt) || isNaN(downPayment) || isNaN(interestRate) || isNaN(loanTerm) ||
annualIncome <= 0 || monthlyDebt < 0 || downPayment < 0 || interestRate <= 0 || loanTerm <= 0) {
resultDiv.innerHTML = "Please enter valid positive numbers for all fields.";
return;
}
// Debt-to-Income Ratio (DTI) guidelines – common lenders use around 43%
var maxDtiRatio = 0.43;
var grossMonthlyIncome = annualIncome / 12;
var maxAllowedMonthlyHousingPayment = (grossMonthlyIncome * maxDtiRatio) – monthlyDebt;
if (maxAllowedMonthlyHousingPayment 0) {
maxLoanAmount = maxAllowedMonthlyHousingPayment * (Math.pow(1 + monthlyInterestRate, numberOfPayments) – 1) / (monthlyInterestRate * Math.pow(1 + monthlyInterestRate, numberOfPayments));
} else {
// If interest rate is 0 (highly unlikely for mortgages, but for completeness)
maxLoanAmount = maxAllowedMonthlyHousingPayment * numberOfPayments;
}
var estimatedMaxHomePrice = maxLoanAmount + downPayment;
resultDiv.innerHTML =
"Estimated Maximum Monthly Housing Payment (Principal, Interest, Taxes, Insurance): $" + maxAllowedMonthlyHousingPayment.toFixed(2) + "" +
"Estimated Maximum Loan Amount: $" + maxLoanAmount.toFixed(2) + "" +
"Estimated Maximum Home Price (including down payment): $" + estimatedMaxHomePrice.toFixed(2) + "" +
"Note: This is an estimate. Actual loan approval and affordability depend on lender policies, credit score, property taxes, homeowner's insurance, and other factors.";
}
.calculator-container {
font-family: sans-serif;
border: 1px solid #ccc;
padding: 20px;
border-radius: 8px;
max-width: 600px;
margin: 20px auto;
background-color: #f9f9f9;
}
.calculator-container h2 {
text-align: center;
margin-bottom: 15px;
color: #333;
}
.calculator-container p {
color: #555;
line-height: 1.6;
}
.calculator-inputs {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 15px;
margin-top: 20px;
margin-bottom: 20px;
}
.input-group {
display: flex;
flex-direction: column;
}
.input-group label {
margin-bottom: 5px;
font-weight: bold;
color: #444;
}
.input-group input[type="number"],
.input-group input[type="text"] {
padding: 10px;
border: 1px solid #ccc;
border-radius: 4px;
font-size: 1em;
}
.calculator-container button {
display: block;
width: 100%;
padding: 12px 20px;
background-color: #007bff;
color: white;
border: none;
border-radius: 4px;
font-size: 1.1em;
cursor: pointer;
transition: background-color 0.3s ease;
margin-top: 10px;
}
.calculator-container button:hover {
background-color: #0056b3;
}
.calculator-result {
margin-top: 25px;
padding: 15px;
background-color: #e9ecef;
border: 1px solid #ced4da;
border-radius: 4px;
}
.calculator-result p {
margin-bottom: 10px;
color: #333;
}
.calculator-result p:last-child {
margin-bottom: 0;
}
.calculator-result small {
color: #6c757d;
font-size: 0.85em;
}
@media (max-width: 500px) {
.calculator-inputs {
grid-template-columns: 1fr;
}
}