Use this calculator to estimate how much house you can afford based on your income, debts, and down payment. Remember, this is an estimate and actual loan approval depends on lender specifics.
.calculator-container {
font-family: sans-serif;
padding: 20px;
border: 1px solid #ccc;
border-radius: 8px;
max-width: 500px;
margin: 20px auto;
background-color: #f9f9f9;
}
.calculator-container h2 {
text-align: center;
margin-bottom: 15px;
color: #333;
}
.calculator-container p {
text-align: center;
font-size: 0.9em;
color: #555;
margin-bottom: 20px;
}
.input-group {
margin-bottom: 15px;
display: flex;
flex-direction: column;
}
.input-group label {
margin-bottom: 5px;
font-weight: bold;
color: #444;
}
.input-group input {
padding: 10px;
border: 1px solid #ddd;
border-radius: 4px;
font-size: 1em;
}
button {
display: block;
width: 100%;
padding: 12px;
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;
}
button:hover {
background-color: #0056b3;
}
.calculator-result {
margin-top: 20px;
padding: 15px;
background-color: #e9ecef;
border: 1px solid #dee2e6;
border-radius: 4px;
font-size: 1.1em;
text-align: center;
color: #333;
}
.calculator-result strong {
color: #007bff;
}
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 = "Error: Please enter valid positive numbers for all fields.";
return;
}
// Lender affordability rules (common guideline, can vary)
// PITI (Principal, Interest, Taxes, Insurance) should not exceed 28% of gross monthly income
// Total debt (PITI + other debts) should not exceed 36% of gross monthly income
var grossMonthlyIncome = annualIncome / 12;
var maxPITI_percentage = 0.28; // 28%
var maxTotalDebt_percentage = 0.36; // 36%
var maxPITI = grossMonthlyIncome * maxPITI_percentage;
var maxTotalDebt = grossMonthlyIncome * maxTotalDebt_percentage;
// We need to estimate taxes and insurance. A common rule of thumb is ~1.2% for taxes and ~0.5% for insurance annually.
// These are highly variable by location and property type. For simplicity, we'll use a combined annual estimate.
// Let's assume estimated annual property taxes + homeowners insurance = 1.5% of potential home price.
// This means monthly taxes & insurance = (0.015 * Home Price) / 12
// This creates a circular dependency, so we'll make an initial assumption or use a simpler approach.
// Simpler approach: Calculate max affordable monthly mortgage payment (P&I)
// Max P&I = Max PITI – Estimated Monthly Taxes & Insurance
// Since we don't know the home price, we can't directly calculate T&I.
// Instead, we'll calculate the maximum loan amount based on the maximum P&I payment allowed.
// Let's reframe: The DTI (Debt-to-Income) ratio is key.
// Max Principal & Interest payment = Max Total Debt – Monthly Debt Payments
var maxPI_payment = maxTotalDebt – monthlyDebt;
if (maxPI_payment <= 0) {
resultDiv.innerHTML = "Affordability Estimate: Based on your income and debts, you may not qualify for a mortgage at this time.";
return;
}
// Calculate the maximum loan amount based on the maximum P&I payment
var monthlyInterestRate = interestRate / 100 / 12;
var numberOfMonths = loanTerm * 12;
// Mortgage payment formula: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1]
// Where M is the monthly payment, P is the principal loan amount, i is the monthly interest rate, and n is the number of months.
// We need to solve for P: P = M [ (1 + i)^n – 1] / [ i(1 + i)^n ]
var maxLoanAmount = 0;
if (monthlyInterestRate > 0) {
maxLoanAmount = maxPI_payment * (Math.pow(1 + monthlyInterestRate, numberOfMonths) – 1) / (monthlyInterestRate * Math.pow(1 + monthlyInterestRate, numberOfMonths));
} else { // Handle 0% interest rate case (unlikely for mortgages but for completeness)
maxLoanAmount = maxPI_payment * numberOfMonths;
}
// Now, estimate the maximum home price by adding the down payment
var estimatedMaxHomePrice = maxLoanAmount + downPayment;
// Display results
var formattedMaxLoan = maxLoanAmount.toLocaleString(undefined, { style: 'currency', currency: 'USD' });
var formattedMaxHomePrice = estimatedMaxHomePrice.toLocaleString(undefined, { style: 'currency', currency: 'USD' });
var formattedMaxPI = maxPI_payment.toLocaleString(undefined, { style: 'currency', currency: 'USD' });
resultDiv.innerHTML = "Estimated Maximum Home Price:" + formattedMaxHomePrice + "" +
"Based on:" +
"- Annual Gross Income: " + annualIncome.toLocaleString(undefined, { style: 'currency', currency: 'USD' }) + "" +
"- Total Monthly Debt (excl. mortgage): " + monthlyDebt.toLocaleString(undefined, { style: 'currency', currency: 'USD' }) + "" +
"- Down Payment: " + downPayment.toLocaleString(undefined, { style: 'currency', currency: 'USD' }) + "" +
"- Estimated Maximum Monthly P&I Payment: " + formattedMaxPI + "" +
"- Estimated Maximum Loan Amount: " + formattedMaxLoan + "" +
"Note: This is a simplified estimate. Actual affordability depends on lender policies, credit score, property taxes, insurance, and HOA fees.";
}