#mortgage-affordability-calculator-wrapper {
font-family: 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
max-width: 800px;
margin: 0 auto;
background: #fff;
padding: 20px;
border-radius: 8px;
box-shadow: 0 2px 10px rgba(0,0,0,0.1);
color: #333;
}
#mortgage-affordability-calculator-wrapper h2 {
color: #2c3e50;
border-bottom: 2px solid #3498db;
padding-bottom: 10px;
margin-bottom: 20px;
}
.calc-grid {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 20px;
margin-bottom: 25px;
}
@media (max-width: 600px) {
.calc-grid {
grid-template-columns: 1fr;
}
}
.input-group {
display: flex;
flex-direction: column;
}
.input-group label {
font-weight: 600;
margin-bottom: 5px;
font-size: 0.95rem;
color: #555;
}
.input-group input, .input-group select {
padding: 10px;
border: 1px solid #ddd;
border-radius: 4px;
font-size: 1rem;
}
.input-group input:focus {
border-color: #3498db;
outline: none;
}
.calc-btn {
background-color: #3498db;
color: white;
border: none;
padding: 15px 30px;
font-size: 1.1rem;
font-weight: bold;
border-radius: 4px;
cursor: pointer;
width: 100%;
transition: background 0.3s;
}
.calc-btn:hover {
background-color: #2980b9;
}
#affordability-result {
margin-top: 30px;
padding: 20px;
background-color: #f8f9fa;
border-radius: 6px;
border-left: 5px solid #2ecc71;
display: none;
}
.result-header {
font-size: 1.2rem;
color: #7f8c8d;
margin-bottom: 10px;
}
.result-value {
font-size: 2.5rem;
font-weight: 800;
color: #2c3e50;
margin-bottom: 20px;
}
.breakdown-row {
display: flex;
justify-content: space-between;
margin-bottom: 8px;
font-size: 0.95rem;
border-bottom: 1px solid #eee;
padding-bottom: 5px;
}
.breakdown-row strong {
color: #34495e;
}
.article-content {
margin-top: 50px;
line-height: 1.6;
color: #444;
}
.article-content h3 {
color: #2c3e50;
margin-top: 25px;
}
.tooltip {
font-size: 0.8rem;
color: #777;
margin-top: 2px;
}
function calculateAffordability() {
// Get Input Values
var income = parseFloat(document.getElementById('annualIncome').value);
var debts = parseFloat(document.getElementById('monthlyDebts').value);
var downPayment = parseFloat(document.getElementById('downPayment').value);
var rate = parseFloat(document.getElementById('interestRate').value);
var years = parseInt(document.getElementById('loanTerm').value);
var tax = parseFloat(document.getElementById('propertyTax').value);
var insurance = parseFloat(document.getElementById('homeInsurance').value);
var dtiSetting = document.getElementById('dtiRatio').value;
// Validation
if (isNaN(income) || income <= 0) {
alert("Please enter a valid annual income.");
return;
}
if (isNaN(debts)) debts = 0;
if (isNaN(downPayment)) downPayment = 0;
if (isNaN(rate) || rate <= 0) {
alert("Please enter a valid interest rate.");
return;
}
if (isNaN(tax)) tax = 0;
if (isNaN(insurance)) insurance = 0;
// Define DTI Ratios based on selection
var frontEndRatio = 0.28;
var backEndRatio = 0.36;
if (dtiSetting === 'standard') {
backEndRatio = 0.43; // Common for Conventional/FHA
} else if (dtiSetting === 'aggressive') {
frontEndRatio = 0.36;
backEndRatio = 0.50; // High end, potentially risky or FHA
}
// Monthly breakdown
var monthlyIncome = income / 12;
var monthlyTax = tax / 12;
var monthlyInsurance = insurance / 12;
var monthlyNonMortgageHousing = monthlyTax + monthlyInsurance;
// Calculate Max Allowable Housing Payment based on Front-End
var maxHousingFront = monthlyIncome * frontEndRatio;
// Calculate Max Allowable Housing Payment based on Back-End
// (Total Debt Allowed – Existing Debts)
var maxTotalDebt = monthlyIncome * backEndRatio;
var maxHousingBack = maxTotalDebt – debts;
// The limiting factor is the lower of the two
var maxHousingPayment = Math.min(maxHousingFront, maxHousingBack);
// If debts are too high, result could be negative
if (maxHousingPayment <= monthlyNonMortgageHousing) {
document.getElementById('affordability-result').style.display = 'block';
document.getElementById('maxHomePriceDisplay').innerText = "$0";
document.getElementById('loanAmountDisplay').innerText = "Debt too high";
return;
}
// Available for Principal & Interest (P&I)
var maxPI = maxHousingPayment – monthlyNonMortgageHousing;
// Calculate Max Loan Amount
// Formula: PV = PMT * (1 – (1+r)^-n) / r
var monthlyRate = rate / 100 / 12;
var numberOfPayments = years * 12;
var maxLoanAmount = maxPI * (1 – Math.pow(1 + monthlyRate, -numberOfPayments)) / monthlyRate;
// Max Home Price
var maxHomePrice = maxLoanAmount + downPayment;
// Display Results
var formatter = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD',
maximumFractionDigits: 0
});
document.getElementById('maxHomePriceDisplay').innerText = formatter.format(maxHomePrice);
document.getElementById('loanAmountDisplay').innerText = formatter.format(maxLoanAmount);
document.getElementById('downPaymentDisplay').innerText = formatter.format(downPayment);
document.getElementById('monthlyPIDisplay').innerText = formatter.format(maxPI);
document.getElementById('monthlyTaxInsDisplay').innerText = formatter.format(monthlyNonMortgageHousing);
document.getElementById('totalMonthlyDisplay').innerText = formatter.format(maxHousingPayment);
document.getElementById('affordability-result').style.display = 'block';
}
Home Affordability Calculator
Total income before taxes.
Credit cards, car loans, student loans, etc.
15 Years
20 Years
30 Years
Conservative (28% / 36%)
Standard (28% / 43%)
Aggressive (36% / 50%)
Front-end / Back-end ratios.
Maximum Home Price You Can Afford
$0
Loan Amount:
$0
Down Payment:
$0
Max Monthly Mortgage Payment (P&I):
$0
Estimated Taxes & Insurance (Monthly):
$0
Total Monthly Housing Cost:
$0
*Calculations based on the selected Debt-to-Income (DTI) ratios. This is an estimate and does not guarantee loan approval.
How Much House Can You Really Afford?
Determining your budget is the first critical step in the home buying process. This Mortgage Affordability Calculator uses the standard debt-to-income (DTI) ratios employed by lenders to estimate your purchasing power.
Understanding the 28/36 Rule
Lenders typically look at two specific ratios to decide how much they will lend you:
- Front-End Ratio (28%): This rule states that your monthly housing costs (principal, interest, taxes, and insurance) should not exceed 28% of your gross monthly income.
- Back-End Ratio (36%): This rule states that your total monthly debt payments (housing costs + credit cards, car loans, student loans, etc.) should not exceed 36% of your gross monthly income.
While some loan programs (like FHA loans) allow for higher ratios (up to 43% or even 50% for the back-end), sticking to the 28/36 rule ensures you aren't "house poor" and maintains financial stability.
Factors Affecting Your Affordability
Several key variables impact how much house you can buy:
- Interest Rate: A lower interest rate significantly increases your buying power. Even a 1% difference can change your affordability by tens of thousands of dollars.
- Down Payment: A larger down payment reduces the loan amount needed, lowering your monthly payments and potentially removing the need for Private Mortgage Insurance (PMI).
- Existing Debt: High monthly debt obligations (like a large car payment) directly reduce the amount of income available for a mortgage, lowering your maximum home price.
- Property Taxes & Insurance: Often overlooked, these costs are part of your monthly payment. Areas with high property taxes will reduce the amount of mortgage principal you can afford.
Improving Your Buying Power
If the result above is lower than expected, consider paying down high-interest consumer debt before applying, saving for a larger down payment to avoid PMI, or shopping around for the best mortgage rates. Improving your credit score can also help you qualify for lower interest rates, directly boosting your affordability.