Use this calculator to estimate how much house you can afford based on your income, debt, and down payment. Understanding your borrowing power is a crucial first step in the home-buying process. This tool helps you get a realistic idea of your price range, allowing you to focus your search and avoid disappointment.
.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-title {
text-align: center;
margin-bottom: 15px;
color: #333;
}
.calculator-description {
font-size: 0.9em;
color: #555;
margin-bottom: 25px;
line-height: 1.5;
}
.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: #444;
font-size: 0.9em;
}
.input-group input {
padding: 10px;
border: 1px solid #ccc;
border-radius: 4px;
font-size: 1em;
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button {
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width: 100%;
padding: 12px 15px;
background-color: #007bff;
color: white;
border: none;
border-radius: 4px;
font-size: 1.1em;
cursor: pointer;
transition: background-color 0.3s ease;
}
button:hover {
background-color: #0056b3;
}
.calculator-result {
margin-top: 20px;
padding: 15px;
background-color: #e9ecef;
border: 1px solid #ced4da;
border-radius: 4px;
font-size: 1.1em;
text-align: center;
color: #333;
}
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) / 100;
var loanTerm = parseFloat(document.getElementById("loanTerm").value);
var propertyTaxRate = parseFloat(document.getElementById("propertyTaxRate").value) / 100;
var homeInsurance = parseFloat(document.getElementById("homeInsurance").value);
var pmiRate = parseFloat(document.getElementById("pmiRate").value) / 100;
var resultElement = document.getElementById("result");
resultElement.innerHTML = ""; // Clear previous results
if (isNaN(annualIncome) || isNaN(monthlyDebt) || isNaN(downPayment) || isNaN(interestRate) || isNaN(loanTerm) || isNaN(propertyTaxRate) || isNaN(homeInsurance) || isNaN(pmiRate)) {
resultElement.innerHTML = "Please enter valid numbers for all fields.";
return;
}
// Lender typically allows PITI (Principal, Interest, Taxes, Insurance) + PMI to be 28-36% of gross monthly income.
// We'll use a conservative 30% for this calculation.
var maxMonthlyHousingPaymentRatio = 0.30;
var monthlyGrossIncome = annualIncome / 12;
var maxMonthlyHousingPayment = monthlyGrossIncome * maxMonthlyHousingPaymentRatio;
// Exclude existing debt from the housing payment calculation
var maxPITI_PMI = maxMonthlyHousingPayment – monthlyDebt;
if (maxPITI_PMI <= 0) {
resultElement.innerHTML = "Based on your income and existing debt, it may be difficult to qualify for a mortgage at this time.";
return;
}
// Estimate the maximum loan amount. This is complex as property tax and insurance depend on home value, which depends on loan amount.
// We'll use an iterative approach or simplify. A common simplification is to assume a loan-to-value (LTV) ratio for the property tax calculation initially,
// or to directly estimate the maximum loan amount based on the monthly P&I payment.
// Let's calculate the maximum loan amount based on the *monthly P&I payment* that can be afforded.
// Max P&I = Max PITI_PMI – Monthly Property Tax – Monthly Home Insurance – Monthly PMI
// We need to make an assumption about the Loan-to-Value (LTV) for initial tax and PMI calculation or iterate.
// A common approach is to assume a max LTV for estimation (e.g., 80% if down payment is 20%).
// For simplicity, let's assume a common LTV like 80% for initial tax/PMI estimate.
// This will be a rough estimate. A more accurate calculation might require iteration.
// Let's try to estimate a max loan amount directly by simplifying.
// If we can determine the maximum *loan amount* (not monthly payment), we can work backward.
// Max Affordable Home Price = Down Payment + Max Loan Amount.
// A simpler approach for a basic calculator is to estimate based on debt-to-income (DTI) ratios,
// where lenders look at total monthly debt payments (including proposed mortgage PITI+PMI) to gross monthly income.
// Let's stick to the 28-36% of gross monthly income for PITI+PMI and solve for the loan amount.
// Let's reformulate: max PITI = maxPITI_PMI – (monthly insurance + monthly PMI)
// We need to estimate monthly property tax and PMI, which depend on the home price.
// Let's assume a loan-to-value ratio (LTV) for estimation. If downPayment is = 0.20 * (annualIncome / maxMonthlyHousingPaymentRatio * 12)) { // very rough check for potential home price
estimatedLTV = 1 – (downPayment / (annualIncome / maxMonthlyHousingPaymentRatio * 12)); // If down payment is substantial
}
if (estimatedLTV > 0.95) estimatedLTV = 0.95; // Cap LTV
if (estimatedLTV < 0.60) estimatedLTV = 0.60; // Floor LTV
var estimatedHomePrice = downPayment / (1 – estimatedLTV); // Initial guess for home price to estimate tax and PMI
var monthlyPropertyTax = (estimatedHomePrice * propertyTaxRate) / 12;
var monthlyPMI = (estimatedHomePrice * estimatedLTV * pmiRate) / 12; // PMI is usually on loan amount, not full price
var monthlyInsurance = homeInsurance / 12;
// Re-calculate max PITI based on estimated monthly expenses
var maxPITI = maxPITI_PMI – monthlyPropertyTax – monthlyInsurance – monthlyPMI;
if (maxPITI <= 0) {
resultElement.innerHTML = "Based on estimated property taxes, insurance, and PMI, your affordable housing payment is too low to qualify for a loan.";
return;
}
// Calculate maximum loan amount using the 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 payments.
// We need to solve for P.
var monthlyInterestRate = interestRate / 12;
var numberOfPayments = loanTerm * 12;
if (monthlyInterestRate 0) {
maxLoanAmount = maxPITI * (Math.pow(1 + monthlyInterestRate, numberOfPayments) – 1) / (monthlyInterestRate * Math.pow(1 + monthlyInterestRate, numberOfPayments));
}
// Adjust for down payment to find maximum affordable home price
var maxAffordableHomePrice = downPayment + maxLoanAmount;
// Re-calculate actual PITI and PMI for the calculated maxAffordableHomePrice to verify
var actualMonthlyPropertyTax = (maxAffordableHomePrice * propertyTaxRate) / 12;
var actualLoanAmount = maxAffordableHomePrice – downPayment;
var actualMonthlyPMI = (actualLoanAmount * pmiRate) / 12; // PMI is on loan amount
var actualMonthlyInsurance = homeInsurance / 12;
var actualPITI = maxPITI_PMI – actualMonthlyPropertyTax – actualMonthlyInsurance – actualPMI;
if (actualPITI 0 && monthlyInterestRate > 0) {
calculatedP_and_I = actualLoanAmount * (monthlyInterestRate * Math.pow(1 + monthlyInterestRate, numberOfPayments)) / (Math.pow(1 + monthlyInterestRate, numberOfPayments) – 1);
}
if (isNaN(maxAffordableHomePrice) || maxAffordableHomePrice <= 0) {
resultElement.innerHTML = "Could not determine a valid affordable home price. Please check your inputs.";
return;
}
resultElement.innerHTML = `
Estimated Maximum Home Price You Can Afford: $${maxAffordableHomePrice.toLocaleString(undefined, { minimumFractionDigits: 0, maximumFractionDigits: 0 })}
(Based on a maximum housing payment of 30% of gross monthly income, excluding existing debts.)Breakdown:
Disclaimer: This is an estimate. Lender approval depends on many factors, including credit score, employment history, and specific loan programs. Consult with a mortgage professional for precise figures.
`;
}