Understanding how much mortgage you can afford is a crucial step in the home-buying process. This calculator helps you estimate your potential borrowing power based on your income, debts, and other financial factors. Remember, this is an estimate, and your actual mortgage approval will depend on a lender's specific criteria.
function calculateMortgageAffordability() {
var grossMonthlyIncome = parseFloat(document.getElementById("grossMonthlyIncome").value);
var otherMonthlyDebt = parseFloat(document.getElementById("otherMonthlyDebt").value);
var downPayment = parseFloat(document.getElementById("downPayment").value);
var interestRate = parseFloat(document.getElementById("interestRate").value) / 100;
var loanTerm = parseFloat(document.getElementById("loanTerm").value);
var resultDiv = document.getElementById("result");
resultDiv.innerHTML = ""; // Clear previous results
if (isNaN(grossMonthlyIncome) || grossMonthlyIncome <= 0 ||
isNaN(otherMonthlyDebt) || otherMonthlyDebt < 0 ||
isNaN(downPayment) || downPayment < 0 ||
isNaN(interestRate) || interestRate <= 0 ||
isNaN(loanTerm) || loanTerm <= 0) {
resultDiv.innerHTML = "Please enter valid positive numbers for all fields.";
return;
}
// Lender Debt-to-Income (DTI) Ratios – common guidelines
// Front-end DTI (Housing) typically 28%
// Back-end DTI (Total Debt) typically 36%
var maxHousingPayment = grossMonthlyIncome * 0.28;
var maxTotalDebtPayment = grossMonthlyIncome * 0.36;
var maxMortgagePayment = maxTotalDebtPayment – otherMonthlyDebt;
// Ensure maxMortgagePayment is not negative
if (maxMortgagePayment 0 && numberOfPayments > 0) {
var factor = Math.pow(1 + monthlyInterestRate, numberOfPayments);
maxLoanAmount = affordableMonthlyPayment * (factor – 1) / (monthlyInterestRate * factor);
}
var estimatedMaxHomePrice = maxLoanAmount + downPayment;
// Format results
var formattedMaxLoanAmount = "$" + maxLoanAmount.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');
var formattedEstimatedMaxHomePrice = "$" + estimatedMaxHomePrice.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');
var formattedAffordableMonthlyPayment = "$" + affordableMonthlyPayment.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');
resultDiv.innerHTML = `
Your Estimated Mortgage Affordability:
Based on your inputs, lenders may approve you for a mortgage loan of up to approximately ${formattedMaxLoanAmount}.
This suggests you could potentially afford a home priced up to approximately ${formattedEstimatedMaxHomePrice}, assuming your down payment.
Your estimated maximum monthly principal and interest (P&I) payment would be around ${formattedAffordableMonthlyPayment}.
Note: This is an estimate. Property taxes, homeowners insurance, and Private Mortgage Insurance (PMI) are not included in this calculation and will increase your actual total monthly housing payment. Actual loan approval depends on lender-specific underwriting.
`;
}
.calculator-container {
font-family: sans-serif;
max-width: 600px;
margin: 20px auto;
padding: 20px;
border: 1px solid #ddd;
border-radius: 8px;
background-color: #f9f9f9;
}
.calculator-container h2 {
text-align: center;
color: #333;
margin-bottom: 20px;
}
.calculator-inputs {
display: grid;
grid-template-columns: 1fr;
gap: 15px;
}
.form-group {
display: flex;
flex-direction: column;
}
.form-group label {
margin-bottom: 5px;
font-weight: bold;
color: #555;
}
.form-group input[type="number"] {
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: 5px;
font-size: 1.1em;
cursor: pointer;
margin-top: 20px;
transition: background-color 0.3s ease;
}
.calculator-container button:hover {
background-color: #0056b3;
}
.calculator-result {
margin-top: 30px;
padding: 15px;
border: 1px solid #eee;
border-radius: 5px;
background-color: #fff;
}
.calculator-result h3 {
margin-top: 0;
color: #007bff;
}
.calculator-result p {
line-height: 1.6;
color: #333;
}
.calculator-result strong {
color: #d9534f;
}
.calculator-result em {
font-size: 0.9em;
color: #777;
}