.calculator-container {
font-family: Arial, 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: 20px;
color: #333;
}
.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;
box-sizing: border-box; /* Ensure padding doesn't affect width */
}
.calculator-container button {
display: block;
width: 100%;
padding: 12px 20px;
background-color: #4CAF50;
color: white;
border: none;
border-radius: 4px;
cursor: pointer;
font-size: 16px;
transition: background-color 0.3s ease;
margin-top: 10px;
}
.calculator-container button:hover {
background-color: #45a049;
}
.calculator-result {
margin-top: 20px;
padding: 15px;
border: 1px solid #ddd;
background-color: #fff;
border-radius: 4px;
font-size: 1.1em;
color: #333;
text-align: center;
}
.calculator-result strong {
color: #4CAF50;
}
function calculateMortgageAffordability() {
var annualIncome = parseFloat(document.getElementById("annualIncome").value);
var downPayment = parseFloat(document.getElementById("downPayment").value);
var existingDebts = parseFloat(document.getElementById("existingDebts").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
// Input validation
if (isNaN(annualIncome) || isNaN(downPayment) || isNaN(existingDebts) || isNaN(interestRate) || isNaN(loanTerm) ||
annualIncome <= 0 || downPayment < 0 || existingDebts < 0 || interestRate <= 0 || loanTerm <= 0) {
resultDiv.innerHTML = "Error: Please enter valid positive numbers for all fields.";
return;
}
// Lender's typical debt-to-income ratio (DTI) thresholds
// Front-end DTI (housing costs) often capped around 28% of gross monthly income
// Back-end DTI (total debt) often capped around 36% of gross monthly income
// These are generalizations and can vary significantly by lender and loan type.
var grossMonthlyIncome = annualIncome / 12;
var maxMonthlyDebtPayment = grossMonthlyIncome * 0.36; // Back-end DTI limit
var allowableHousingPayment = grossMonthlyIncome * 0.28; // Front-end DTI limit
var currentMonthlyDebtObligations = existingDebts;
// Calculate the maximum monthly mortgage payment we can afford
// This is limited by the overall DTI ratio, after accounting for existing debts.
var maxAffordableMortgagePayment = maxMonthlyDebtPayment – currentMonthlyDebtObligations;
// The actual affordable housing payment is also limited by the front-end DTI ratio.
// We should take the minimum of the two constraints for affordability.
var maxAffordableHousingPayment = Math.min(maxAffordableMortgagePayment, allowableHousingPayment);
if (maxAffordableHousingPayment 0) {
maxLoanAmount = maxAffordableHousingPayment * (Math.pow(1 + monthlyInterestRate, numberOfPayments) – 1) / (monthlyInterestRate * Math.pow(1 + monthlyInterestRate, numberOfPayments));
} else {
// Handle zero interest rate (though rare for mortgages)
maxLoanAmount = maxAffordableHousingPayment * numberOfPayments;
}
// The maximum affordable home price is the max loan amount plus the down payment.
var maxAffordableHomePrice = maxLoanAmount + downPayment;
// Display results
resultDiv.innerHTML = "Based on the information provided:" +
"Your estimated maximum affordable home price is: $" + maxAffordableHomePrice.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,') + "" +
"(This includes your down payment of $" + downPayment.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,') + ")" +
"Your estimated maximum loan amount is: $" + maxLoanAmount.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,') + "" +
"Your estimated maximum monthly mortgage payment (P&I) is: $" + maxAffordableHousingPayment.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,') + "";
}
Understanding how much house you can afford is a crucial first step in the home-buying process. This Mortgage Affordability Calculator helps you estimate the maximum home price you might qualify for, considering your financial situation. It's important to remember that this is an estimate, and actual loan approval depends on many factors, including lender policies, credit score, employment history, and the specific property.
How the Mortgage Affordability Calculator Works
Lenders use specific ratios to determine how much they are willing to lend you. The two most common are:
Front-End Debt-to-Income Ratio (DTI): This ratio compares your estimated monthly housing expenses (principal, interest, property taxes, and homeowner's insurance – often called PITI) to your gross monthly income. Lenders typically want this to be no more than 28% of your gross monthly income.
Back-End Debt-to-Income Ratio (DTI): This ratio compares all your monthly debt obligations (including your potential mortgage payment, car loans, student loans, credit card minimum payments, etc.) to your gross monthly income. Lenders generally prefer this to be no more than 36% of your gross monthly income, though some may go up to 43% or even higher for certain loan programs.
Our calculator uses these common DTI limits to estimate your maximum affordable monthly mortgage payment. It then works backward using the loan term and interest rate you provide to calculate the maximum loan amount you could service with that payment. Finally, it adds your down payment to estimate the maximum home price you can afford.
Key Inputs Explained:
Annual Household Income: The total combined income of all borrowers from all sources before taxes.
Down Payment: The amount of cash you plan to put down on the home purchase. A larger down payment reduces the loan amount needed and can improve your chances of approval.
Monthly Debt Payments: The sum of your minimum monthly payments for all other debts, such as credit cards, car loans, student loans, and personal loans. Don't include utilities or rent.
Estimated Mortgage Interest Rate: The expected annual interest rate on the mortgage. This significantly impacts your monthly payment. Rates can vary based on your credit score, market conditions, and loan type.
Loan Term (Years): The length of time over which you will repay the mortgage loan. Common terms are 15, 20, or 30 years. Longer terms result in lower monthly payments but more interest paid over time.
Important Considerations:
Estimates Only: This calculator provides an estimate. Actual mortgage approval depends on a lender's specific underwriting guidelines.
PITI vs. P&I: Our calculator primarily estimates your principal and interest (P&I) payment based on DTI limits. Remember that your total monthly housing cost (PITI) will be higher once property taxes and homeowner's insurance are included.
Credit Score: Your credit score is a major factor. A higher score generally leads to better interest rates and loan terms.
Loan Programs: Different loan programs (e.g., FHA, VA, Conventional) have varying DTI requirements and down payment options.
Closing Costs: Beyond the down payment, you'll need funds for closing costs, which can include appraisal fees, title insurance, origination fees, and more.
Use this calculator as a tool to guide your budget and understand your potential borrowing power. For a precise figure, consult with a mortgage lender or broker.