#mortgage-affordability-calculator-container {
font-family: 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
max-width: 800px;
margin: 0 auto;
color: #333;
line-height: 1.6;
}
.mac-calculator-card {
background: #ffffff;
border: 1px solid #e0e0e0;
border-radius: 8px;
box-shadow: 0 4px 12px rgba(0,0,0,0.05);
padding: 30px;
margin-bottom: 40px;
}
.mac-header {
text-align: center;
margin-bottom: 25px;
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.mac-header h2 {
margin: 0;
color: #2c3e50;
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margin-top: 5px;
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.mac-grid {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 20px;
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@media (max-width: 600px) {
.mac-grid {
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.mac-input-group {
margin-bottom: 15px;
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.mac-input-group label {
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margin-bottom: 5px;
font-weight: 600;
font-size: 14px;
color: #34495e;
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.mac-input-wrapper {
position: relative;
}
.mac-input-wrapper input {
width: 100%;
padding: 10px 10px 10px 30px; /* Space for symbol */
border: 1px solid #dcdcdc;
border-radius: 4px;
font-size: 16px;
box-sizing: border-box;
transition: border-color 0.3s;
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.mac-input-wrapper input:focus {
border-color: #3498db;
outline: none;
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.mac-symbol {
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.mac-suffix {
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.mac-btn {
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cursor: pointer;
width: 100%;
margin-top: 10px;
transition: background-color 0.2s;
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.mac-btn:hover {
background-color: #219150;
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.mac-results {
background-color: #f8f9fa;
border-radius: 6px;
padding: 20px;
margin-top: 25px;
display: none; /* Hidden by default */
border-left: 5px solid #27ae60;
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.mac-result-header {
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.mac-result-value {
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.mac-breakdown {
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.mac-breakdown-item span {
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.mac-article {
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function calculateAffordability() {
// Get Input Values
var annualIncome = parseFloat(document.getElementById('annualIncome').value) || 0;
var monthlyDebt = parseFloat(document.getElementById('monthlyDebt').value) || 0;
var downPayment = parseFloat(document.getElementById('downPayment').value) || 0;
var interestRate = parseFloat(document.getElementById('interestRate').value) || 0;
var loanTermYears = parseFloat(document.getElementById('loanTerm').value) || 30;
var taxRate = parseFloat(document.getElementById('taxRate').value) || 0;
var insRate = parseFloat(document.getElementById('insRate').value) || 0;
var hoaFees = parseFloat(document.getElementById('hoaFees').value) || 0;
// Validate essential inputs
if (annualIncome <= 0) {
alert("Please enter a valid annual income.");
return;
}
// Calculate Monthly Income
var monthlyGrossIncome = annualIncome / 12;
// 1. Determine Max Allowable Housing Payment based on DTI Rules
// Front-End Ratio (28% of Income)
var maxHousingFront = monthlyGrossIncome * 0.28;
// Back-End Ratio (36% of Income – Debts)
var maxHousingBack = (monthlyGrossIncome * 0.36) – monthlyDebt;
// The limiting factor is the lower of the two
var maxAffordableMonthlyPayment = Math.min(maxHousingFront, maxHousingBack);
// If debts are too high, affordability might be zero or negative
if (maxAffordableMonthlyPayment <= hoaFees) {
displayResults(0, 0, 0, 0, 0, hoaFees);
return;
}
// 2. Solve for Max Home Price
// MaxPayment = (Loan * M_Factor) + (HomePrice * TaxFactor) + (HomePrice * InsFactor) + HOA
// HomePrice = Loan + DownPayment
// var P = HomePrice, D = DownPayment, L = Loan (P-D)
// MaxPayment – HOA = (P-D)*M_Factor + P*TaxFactor + P*InsFactor
// MaxPayment – HOA = P*M_Factor – D*M_Factor + P*TaxFactor + P*InsFactor
// MaxPayment – HOA + D*M_Factor = P * (M_Factor + TaxFactor + InsFactor)
// P = (MaxPayment – HOA + D*M_Factor) / (M_Factor + TaxFactor + InsFactor)
var r = (interestRate / 100) / 12;
var n = loanTermYears * 12;
// Mortgage Factor (Principal + Interest per dollar of loan)
var mortgageFactor = 0;
if (interestRate === 0) {
mortgageFactor = 1 / n;
} else {
mortgageFactor = (r * Math.pow(1 + r, n)) / (Math.pow(1 + r, n) – 1);
}
// Tax and Insurance Factors (Monthly cost per dollar of home price)
var taxFactor = (taxRate / 100) / 12;
var insFactor = (insRate / 100) / 12;
var numerator = maxAffordableMonthlyPayment – hoaFees + (downPayment * mortgageFactor);
var denominator = mortgageFactor + taxFactor + insFactor;
var maxHomePrice = numerator / denominator;
// Edge case: if maxHomePrice < downPayment, it implies the math is skewed by negative loan needed (math artifact).
// But realistically, you can afford at least the down payment.
// However, the formula assumes standard mortgage. If maxHomePrice < DownPayment, it means you can't borrow anything.
if (maxHomePrice < 0) maxHomePrice = 0;
// Recalculate components for display based on the derived Max Home Price
var loanAmount = Math.max(0, maxHomePrice – downPayment);
var monthlyPI = loanAmount * mortgageFactor;
var monthlyTax = maxHomePrice * taxFactor;
var monthlyIns = maxHomePrice * insFactor;
var totalMonthly = monthlyPI + monthlyTax + monthlyIns + hoaFees;
displayResults(maxHomePrice, totalMonthly, monthlyPI, monthlyTax, monthlyIns, hoaFees);
}
function displayResults(price, payment, pi, tax, ins, hoa) {
// Formatting helper
var fmt = new Intl.NumberFormat('en-US', { style: 'currency', currency: 'USD', maximumFractionDigits: 0 });
document.getElementById('resultHomePrice').innerText = fmt.format(price);
document.getElementById('resultMonthlyPayment').innerText = fmt.format(payment) + " / mo";
document.getElementById('valPI').innerText = fmt.format(pi);
document.getElementById('valTax').innerText = fmt.format(tax);
document.getElementById('valIns').innerText = fmt.format(ins);
document.getElementById('valHOA').innerText = fmt.format(hoa);
// Show results div
document.getElementById('macResults').style.display = 'block';
// Scroll to results
document.getElementById('macResults').scrollIntoView({ behavior: 'smooth' });
}
Mortgage Affordability Calculator
Determine exactly how much house you can afford based on your income and debts.
$
$
$
%
Years
$
%
%
You can afford a home price of:
$0
Estimated Monthly Payment:
$0
Principal & Interest
$0
Property Taxes
$0
Home Insurance
$0
HOA Fees
$0
How Is Mortgage Affordability Calculated?
Understanding how much house you can afford involves analyzing your Debt-to-Income (DTI) ratio. Lenders typically look at two specific ratios to determine your borrowing power:
- The Front-End Ratio (28%): This rule suggests that your housing costs (mortgage principal, interest, taxes, insurance, and HOA) should not exceed 28% of your gross monthly income.
- The Back-End Ratio (36%): This rule suggests that your total monthly debt payments (housing costs plus student loans, credit cards, car payments, etc.) should not exceed 36% of your gross monthly income.
This calculator determines the maximum monthly payment allowed by both ratios and uses the lower (more conservative) figure to calculate your maximum home price.
Key Factors Affecting Your Budget
Several variables impact your purchasing power beyond just the price of the home:
- Interest Rates: A higher interest rate increases your monthly payment, significantly reducing the loan amount you qualify for.
- Property Taxes: High local property tax rates eat into your monthly budget, lowering the potential sticker price of the home you can afford.
- Down Payment: A larger down payment reduces the loan amount needed and typically removes Private Mortgage Insurance (PMI), improving affordability.
- Existing Debt: Reducing monthly obligations like credit card debt or car loans frees up more of your income for a mortgage payment.
Improving Your Affordability
If the result isn't what you hoped for, consider paying down high-interest debt to improve your DTI ratio, saving for a larger down payment, or looking in areas with lower property taxes. Even a small reduction in interest rates can boost your buying power by tens of thousands of dollars.