.mac-row {
display: flex;
flex-wrap: wrap;
margin: 0 -10px;
}
.mac-col {
flex: 1;
padding: 0 10px;
min-width: 250px;
margin-bottom: 20px;
}
.mac-label {
display: block;
margin-bottom: 8px;
font-weight: 600;
color: #333;
font-size: 14px;
}
.mac-input {
width: 100%;
padding: 12px;
border: 1px solid #ddd;
border-radius: 6px;
font-size: 16px;
box-sizing: border-box;
transition: border-color 0.3s;
}
.mac-input:focus {
border-color: #0073aa;
outline: none;
}
.mac-btn {
background-color: #0073aa;
color: white;
border: none;
padding: 15px 30px;
font-size: 18px;
font-weight: bold;
border-radius: 6px;
cursor: pointer;
width: 100%;
transition: background-color 0.3s;
}
.mac-btn:hover {
background-color: #005177;
}
.mac-result-box {
background-color: #f8f9fa;
border-left: 5px solid #0073aa;
padding: 20px;
margin-top: 30px;
display: none;
}
.mac-result-title {
font-size: 16px;
color: #666;
margin-bottom: 5px;
}
.mac-result-value {
font-size: 32px;
color: #2c3e50;
font-weight: 800;
margin-bottom: 15px;
}
.mac-breakdown {
margin-top: 15px;
border-top: 1px solid #eee;
padding-top: 15px;
}
.mac-breakdown-item {
display: flex;
justify-content: space-between;
margin-bottom: 8px;
font-size: 14px;
color: #555;
}
.mac-disclaimer {
font-size: 12px;
color: #999;
margin-top: 10px;
font-style: italic;
}
.mac-article {
margin-top: 50px;
line-height: 1.6;
color: #333;
}
.mac-article h2 {
font-size: 24px;
margin-bottom: 15px;
color: #2c3e50;
}
.mac-article h3 {
font-size: 20px;
margin-top: 25px;
margin-bottom: 10px;
color: #2c3e50;
}
.mac-article p {
margin-bottom: 15px;
}
.mac-article ul {
margin-bottom: 15px;
padding-left: 20px;
}
.mac-article li {
margin-bottom: 8px;
}
function calculateAffordability() {
// Get inputs
var incomeInput = document.getElementById('mac-income').value;
var debtsInput = document.getElementById('mac-debts').value;
var downPaymentInput = document.getElementById('mac-down-payment').value;
var interestInput = document.getElementById('mac-interest').value;
var termInput = document.getElementById('mac-term').value;
var taxRateInput = document.getElementById('mac-tax-rate').value;
var insRateInput = document.getElementById('mac-ins-rate').value;
// Validate numbers
var annualIncome = parseFloat(incomeInput);
var monthlyDebts = parseFloat(debtsInput) || 0;
var downPayment = parseFloat(downPaymentInput) || 0;
var interestRate = parseFloat(interestInput);
var years = parseInt(termInput);
var annualTaxRate = parseFloat(taxRateInput) || 0; // percentage
var annualInsRate = parseFloat(insRateInput) || 0; // percentage
if (isNaN(annualIncome) || annualIncome <= 0 || isNaN(interestRate) || isNaN(years)) {
alert("Please enter valid income, interest rate, and loan term values.");
return;
}
// 1. Calculate Allowable Monthly Budget based on 28/36 Rule
var monthlyGrossIncome = annualIncome / 12;
// Front-end ratio (28% of gross income)
var limitFront = monthlyGrossIncome * 0.28;
// Back-end ratio (36% of gross income minus debts)
var limitBack = (monthlyGrossIncome * 0.36) – monthlyDebts;
// Lenders typically take the LOWER of the two
var maxMonthlyBudget = Math.min(limitFront, limitBack);
// If debts are too high, budget might be 0 or negative
if (maxMonthlyBudget <= 0) {
document.getElementById('mac-result').style.display = 'block';
document.getElementById('mac-max-price').innerText = "$0";
document.getElementById('mac-total-monthly').innerText = "Debt too high";
document.getElementById('mac-pi-val').innerText = "-";
document.getElementById('mac-tax-val').innerText = "-";
document.getElementById('mac-ins-val').innerText = "-";
return;
}
// 2. Solve for Loan Amount (P)
// Formula involves P&I plus Escrow (Tax + Ins)
// MonthlyPayment = P * Factor + (HomePrice * (TaxRate + InsRate)/12)
// Since HomePrice = P + DownPayment
// MaxBudget = P * Factor + ((P + Down) * TotalEscrowRate)
var r = (interestRate / 100) / 12;
var n = years * 12;
// Mortgage Factor (Principal & Interest per dollar borrowed)
var factor = 0;
if (r === 0) {
factor = 1 / n;
} else {
factor = (r * Math.pow(1 + r, n)) / (Math.pow(1 + r, n) – 1);
}
// Monthly Escrow Rate (Tax + Insurance as a decimal per month)
var totalEscrowRateMonthly = (annualTaxRate + annualInsRate) / 100 / 12;
// Algebra:
// MaxBudget = P * factor + (P * totalEscrowRateMonthly) + (DownPayment * totalEscrowRateMonthly)
// MaxBudget – (DownPayment * totalEscrowRateMonthly) = P * (factor + totalEscrowRateMonthly)
// P = (MaxBudget – (Down * EscrowRate)) / (Factor + EscrowRate)
var numerator = maxMonthlyBudget – (downPayment * totalEscrowRateMonthly);
var denominator = factor + totalEscrowRateMonthly;
var maxLoanAmount = numerator / denominator;
// Edge case: If upkeep on downpayment alone is higher than budget
if (maxLoanAmount < 0) {
maxLoanAmount = 0;
}
var maxHomePrice = maxLoanAmount + downPayment;
// 3. Calculate components for display
var monthlyTax = maxHomePrice * (annualTaxRate / 100 / 12);
var monthlyIns = maxHomePrice * (annualInsRate / 100 / 12);
var monthlyPI = maxLoanAmount * factor;
var totalMonthly = monthlyPI + monthlyTax + monthlyIns;
// 4. Update UI
document.getElementById('mac-result').style.display = 'block';
var formatter = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD',
maximumFractionDigits: 0
});
document.getElementById('mac-max-price').innerText = formatter.format(maxHomePrice);
document.getElementById('mac-pi-val').innerText = formatter.format(monthlyPI);
document.getElementById('mac-tax-val').innerText = formatter.format(monthlyTax);
document.getElementById('mac-ins-val').innerText = formatter.format(monthlyIns);
document.getElementById('mac-total-monthly').innerText = formatter.format(totalMonthly);
}
How Much House Can I Afford?
Determining your home buying budget is the critical first step in your real estate journey. This Mortgage Affordability Calculator goes beyond simple estimates by using the standard Debt-to-Income (DTI) ratios that lenders actually use to approve loans.
Understanding the 28/36 Rule
Most financial advisors and mortgage lenders rely on the "28/36 rule" to decide how much they are willing to lend you. Here is how it breaks down:
- The Front-End Ratio (28%): Your monthly housing costs (principal, interest, taxes, and insurance) should not exceed 28% of your gross monthly income.
- The Back-End Ratio (36%): Your total monthly debt payments (housing costs plus credit cards, car loans, student loans, etc.) should not exceed 36% of your gross monthly income.
Our calculator computes both ratios based on your inputs and uses the lower number to determine your safe maximum budget. This ensures you aren't "house poor" and can maintain your lifestyle comfortably.
Key Factors Affecting Your Affordability
While income is important, several other variables play a massive role in your purchasing power:
1. Down Payment
The more cash you put down upfront, the more expensive the home you can buy for the same monthly payment. A larger down payment also reduces the loan amount, which lowers the interest you pay over the life of the loan.
2. Monthly Debts
Existing debts are the biggest killer of mortgage affordability. A $500 monthly car payment can reduce your home buying power by roughly $75,000 to $100,000 depending on interest rates. paying down high-interest debt before applying for a mortgage is often the best strategy to increase your budget.
3. Interest Rates
Even a small fluctuation in interest rates can drastically change your buying power. When rates rise, your monthly payment increases, which lowers the maximum loan amount you can qualify for under the 28/36 rule.
4. Property Taxes and Insurance
Many buyers forget to factor in property taxes and homeowners insurance. These costs are usually bundled into your monthly mortgage payment (escrow). In areas with high property taxes, your purchasing power will be significantly lower compared to low-tax areas, even with the same income.
How to Use This Result
The "Maximum Home Price" displayed above is an estimate of the ceiling of your budget. We recommend aiming for a purchase price slightly below this maximum to account for maintenance costs, utilities, and emergency savings. Always consult with a qualified mortgage professional to get a pre-approval letter before shopping for homes.