:root {
–primary-color: #2c3e50;
–accent-color: #27ae60;
–bg-light: #f9f9f9;
–text-color: #333;
–border-radius: 8px;
}
body {
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
line-height: 1.6;
color: var(–text-color);
margin: 0;
padding: 20px;
}
.calc-wrapper {
max-width: 800px;
margin: 0 auto;
border: 1px solid #e1e1e1;
border-radius: var(–border-radius);
box-shadow: 0 4px 6px rgba(0,0,0,0.05);
background: #fff;
overflow: hidden;
}
.calc-header {
background: var(–primary-color);
color: #fff;
padding: 20px;
text-align: center;
}
.calc-header h2 {
margin: 0;
font-size: 24px;
}
.calc-body {
padding: 30px;
display: grid;
grid-template-columns: 1fr 1fr;
gap: 30px;
}
@media (max-width: 768px) {
.calc-body {
grid-template-columns: 1fr;
}
}
.form-group {
margin-bottom: 15px;
}
.form-group label {
display: block;
margin-bottom: 5px;
font-weight: 600;
font-size: 14px;
}
.input-wrapper {
position: relative;
}
.input-wrapper input {
width: 100%;
padding: 10px 10px 10px 25px;
border: 1px solid #ccc;
border-radius: 4px;
font-size: 16px;
box-sizing: border-box;
}
.input-wrapper span {
position: absolute;
left: 10px;
top: 50%;
transform: translateY(-50%);
color: #777;
}
.calc-actions {
grid-column: 1 / -1;
text-align: center;
margin-top: 10px;
}
button.calc-btn {
background: var(–accent-color);
color: #fff;
border: none;
padding: 15px 40px;
font-size: 18px;
font-weight: bold;
border-radius: 4px;
cursor: pointer;
transition: background 0.3s;
}
button.calc-btn:hover {
background: #219150;
}
.results-section {
grid-column: 1 / -1;
background: var(–bg-light);
padding: 20px;
border-radius: var(–border-radius);
margin-top: 20px;
display: none;
}
.result-card {
text-align: center;
margin-bottom: 20px;
padding-bottom: 20px;
border-bottom: 1px solid #ddd;
}
.result-card h3 {
margin: 0 0 10px;
color: var(–primary-color);
}
.result-big {
font-size: 36px;
font-weight: bold;
color: var(–accent-color);
}
.result-details {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 15px;
font-size: 14px;
}
.detail-row {
display: flex;
justify-content: space-between;
padding: 5px 0;
border-bottom: 1px dotted #ccc;
}
.seo-content {
max-width: 800px;
margin: 40px auto;
}
.seo-content h2 {
color: var(–primary-color);
border-bottom: 2px solid var(–accent-color);
padding-bottom: 10px;
margin-top: 30px;
}
.seo-content h3 {
color: var(–primary-color);
margin-top: 25px;
}
.seo-content p, .seo-content ul {
color: #555;
font-size: 16px;
}
.seo-content li {
margin-bottom: 10px;
}
.error-msg {
color: red;
text-align: center;
grid-column: 1 / -1;
display: none;
}
Understanding How Much House You Can Afford
Buying a home is one of the most significant financial decisions you will make in your lifetime. Before you start browsing listings or attending open houses, it is crucial to determine a realistic budget. This Mortgage Affordability Calculator helps you estimate the maximum home price you can comfortably afford based on your income, debts, and current interest rates.
How Is Affordability Calculated?
Lenders primarily use two metrics called Debt-to-Income (DTI) ratios to decide how much money they are willing to lend you. This calculator uses the standard "28/36 rule" used by most conventional lenders:
- 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 (including your new mortgage plus credit cards, student loans, car payments, etc.) should not exceed 36% of your gross monthly income.
The calculator determines the maximum monthly payment allowed under both rules and uses the lower of the two to determine your maximum loan amount.
Key Factors That Impact Your Buying Power
Several variables can significantly increase or decrease the price of the home you can afford:
1. Interest Rates
Even a small change in interest rates can drastically alter your purchasing power. For example, on a $300,000 loan, a 1% increase in interest rate can increase your monthly payment by over $180, potentially pushing a home out of your DTI range.
2. Down Payment
A larger down payment does two things: it reduces the loan amount (lowering monthly payments) and directly increases the maximum home price you can buy (Loan Amount + Down Payment = Home Price).
3. Recurring Debts
High monthly obligations like car leases or student loans reduce your "Back-End" allowance. Paying off a $400/month car loan could theoretically allow you to afford roughly $60,000 – $80,000 more in mortgage principal, depending on rates.
What are PITI Costs?
When lenders look at affordability, they don't just look at the loan repayment. They look at PITI:
- Principal: The money that goes toward paying down the loan balance.
- Interest: The cost of borrowing the money.
- Taxes: Property taxes charged by your local government.
- Insurance: Homeowners insurance to protect the property.
This calculator subtracts estimated taxes and insurance from your maximum allowable payment to see how much is left for Principal and Interest, which determines the loan size.
Disclaimer
This calculator provides an estimate based on standard financial ratios. Actual affordability may vary based on your credit score, loan type (FHA, VA, USDA), and current lender guidelines. Always consult with a qualified mortgage professional for a pre-approval.
function calculateMortgageAffordability() {
// 1. Get Input Values
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 propertyTax = parseFloat(document.getElementById('propertyTax').value);
var homeInsurance = parseFloat(document.getElementById('homeInsurance').value);
var frontEndRatio = parseFloat(document.getElementById('frontEndRatio').value);
var backEndRatio = parseFloat(document.getElementById('backEndRatio').value);
// 2. Validation
var errorDiv = document.getElementById('errorMessage');
var resultsDiv = document.getElementById('resultsSection');
if (isNaN(annualIncome) || isNaN(interestRate) || isNaN(loanTerm)) {
errorDiv.style.display = 'block';
resultsDiv.style.display = 'none';
return;
} else {
errorDiv.style.display = 'none';
}
// Handle optional fields as 0 if empty/NaN
if (isNaN(monthlyDebt)) monthlyDebt = 0;
if (isNaN(downPayment)) downPayment = 0;
if (isNaN(propertyTax)) propertyTax = 0;
if (isNaN(homeInsurance)) homeInsurance = 0;
// 3. Calculation Logic
var monthlyGrossIncome = annualIncome / 12;
var monthlyTax = propertyTax / 12;
var monthlyInsurance = homeInsurance / 12;
// Calculate Limits based on Ratios
// Front End Limit: Housing costs only
var limitFrontEnd = monthlyGrossIncome * frontEndRatio;
// Back End Limit: Housing costs + Other Debts
var limitBackEnd = (monthlyGrossIncome * backEndRatio) – monthlyDebt;
// The maximum allowable PITI is the lesser of the two
var maxAllowablePITI = Math.min(limitFrontEnd, limitBackEnd);
// Determine Limiting Factor for display
var limitingFactor = (limitFrontEnd < limitBackEnd) ? "Front-End Ratio (Income)" : "Back-End Ratio (Debts)";
if (maxAllowablePITI 0) {
var r = (interestRate / 100) / 12; // Monthly interest rate
var n = loanTerm * 12; // Total number of months
if (r === 0) {
maxLoanAmount = availableForPI * n;
} else {
// Present Value Formula: PV = PMT * (1 – (1+r)^-n) / r
maxLoanAmount = availableForPI * ( (1 – Math.pow(1 + r, -n)) / r );
}
} else {
availableForPI = 0;
}
var maxHomePrice = maxLoanAmount + downPayment;
// 4. Output Results
resultsDiv.style.display = 'block';
// Helper for formatting currency
var formatter = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD',
maximumFractionDigits: 0
});
document.getElementById('resultHomePrice').innerText = formatter.format(maxHomePrice);
document.getElementById('resultMaxPayment').innerText = formatter.format(maxAllowablePITI) + " /mo";
document.getElementById('resultPI').innerText = formatter.format(availableForPI);
document.getElementById('resultTax').innerText = formatter.format(monthlyTax);
document.getElementById('resultIns').innerText = formatter.format(monthlyInsurance);
document.getElementById('resultLoanAmount').innerText = formatter.format(maxLoanAmount);
document.getElementById('resultDownPayment').innerText = formatter.format(downPayment);
document.getElementById('resultLimitingFactor').innerText = limitingFactor;
// Scroll to results
resultsDiv.scrollIntoView({ behavior: 'smooth' });
}