.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: repeat(auto-fit, minmax(250px, 1fr));
gap: 15px;
margin-bottom: 20px;
}
.input-group {
display: flex;
flex-direction: column;
}
.input-group label {
margin-bottom: 5px;
font-weight: bold;
color: #555;
}
.input-group input {
padding: 10px;
border: 1px solid #ccc;
border-radius: 4px;
font-size: 1rem;
}
.calculator-container button {
display: block;
width: 100%;
padding: 12px 20px;
background-color: #4CAF50;
color: white;
border: none;
border-radius: 4px;
cursor: pointer;
font-size: 1.1rem;
margin-top: 10px;
}
.calculator-container button:hover {
background-color: #45a049;
}
.calculator-result {
margin-top: 25px;
padding: 15px;
background-color: #e7f3fe;
border: 1px solid #b3d7fc;
border-radius: 4px;
text-align: center;
font-size: 1.1rem;
color: #333;
}
.calculator-result strong {
color: #4CAF50;
}
function calculateMortgageAffordability() {
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");
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;
}
// Rule of thumb: Housing expenses (PITI) should not exceed 28% of gross monthly income
var maxPITI = (annualIncome / 12) * 0.28;
// Rule of thumb: Total debt payments (including potential mortgage PITI) should not exceed 36% of gross monthly income
var maxTotalDebt = (annualIncome / 12) * 0.36;
// Calculate the maximum affordable monthly mortgage payment (PITI)
var affordablePITI = Math.min(maxPITI, maxTotalDebt – monthlyDebt);
if (affordablePITI 0) {
maxLoanAmount = affordablePITI * (1 – Math.pow(1 + monthlyInterestRate, -numberOfPayments)) / monthlyInterestRate;
} else {
// Handle case where interest rate is 0% (though unlikely for mortgages)
maxLoanAmount = affordablePITI * numberOfPayments;
}
// The maximum affordable home price is the maximum loan amount plus the down payment
var maxAffordablePrice = maxLoanAmount + downPayment;
resultDiv.innerHTML = "Your estimated maximum affordable home price is: $" + maxAffordablePrice.toFixed(2) + "." +
"This is based on an estimated maximum monthly PITI (Principal, Interest, Taxes, Insurance) of: $" + affordablePITI.toFixed(2) + ".";
}
Understanding Mortgage Affordability
Determining how much house you can afford is a crucial step in the home-buying process. Lenders use various metrics to assess your borrowing capacity, but understanding these yourself can empower you to set realistic expectations and search for homes within your true budget. This calculator helps you estimate your potential mortgage affordability based on common lending guidelines.
Key Factors Influencing Affordability:
Annual Household Income: This is the primary driver of affordability. Lenders look at your gross income (before taxes) to determine how much you can realistically borrow.
Existing Monthly Debt Payments: This includes car loans, student loans, credit card payments, and any other recurring debt obligations (excluding your current rent or mortgage, as that will be replaced). High existing debt can significantly reduce how much you can borrow for a mortgage.
Down Payment: A larger down payment reduces the loan amount needed, making the home more affordable and potentially improving your loan terms. It also affects your Loan-to-Value (LTV) ratio, which lenders consider.
Interest Rate: Even small changes in the interest rate can have a substantial impact on your monthly payments and the total amount of interest paid over the life of the loan. Higher interest rates mean lower borrowing power for the same monthly payment.
Loan Term: The length of the mortgage (e.g., 15 years, 30 years) affects your monthly payment. Shorter terms have higher monthly payments but less total interest paid, while longer terms have lower monthly payments but more total interest paid.
How the Calculator Works:
This calculator uses two common "rules of thumb" that lenders often consider:
The 28% Rule: Your total monthly housing expenses (including principal, interest, property taxes, and homeowner's insurance – often referred to as PITI) should ideally not exceed 28% of your gross monthly income.
The 36% Rule: Your total monthly debt obligations (including your potential new mortgage PITI payment plus all other debts like car loans, student loans, and credit card minimums) should not exceed 36% of your gross monthly income.
The calculator first determines the maximum affordable monthly PITI payment based on these rules. It then estimates the maximum loan amount you could qualify for with that monthly payment, given your specified interest rate and loan term. Finally, it adds your down payment to this loan amount to estimate the maximum affordable home price.
Disclaimer: This calculator provides an estimate for informational purposes only. Actual loan approval and amounts depend on a lender's specific underwriting criteria, your credit score, employment history, and other financial factors. It's always best to speak with a mortgage professional for a precise pre-approval.