#mortgage-affordability-tool-container .calc-box {
background: #ffffff;
border: 1px solid #e0e0e0;
border-radius: 8px;
padding: 30px;
box-shadow: 0 4px 12px rgba(0,0,0,0.05);
margin-bottom: 40px;
}
#mortgage-affordability-tool-container h2 {
margin-top: 0;
color: #2c3e50;
font-size: 24px;
text-align: center;
margin-bottom: 25px;
}
#mortgage-affordability-tool-container .input-group {
margin-bottom: 20px;
}
#mortgage-affordability-tool-container label {
display: block;
margin-bottom: 8px;
font-weight: 600;
font-size: 14px;
color: #555;
}
#mortgage-affordability-tool-container input[type="number"] {
width: 100%;
padding: 12px;
border: 1px solid #ccc;
border-radius: 4px;
font-size: 16px;
box-sizing: border-box;
transition: border-color 0.3s;
}
#mortgage-affordability-tool-container input[type="number"]:focus {
border-color: #0073aa;
outline: none;
}
#mortgage-affordability-tool-container .calc-btn {
background-color: #0073aa;
color: white;
border: none;
padding: 15px 30px;
font-size: 16px;
font-weight: bold;
border-radius: 4px;
cursor: pointer;
width: 100%;
margin-top: 10px;
transition: background-color 0.2s;
}
#mortgage-affordability-tool-container .calc-btn:hover {
background-color: #005177;
}
#mortgage-affordability-tool-container .results-section {
margin-top: 30px;
padding-top: 20px;
border-top: 2px solid #f0f0f0;
display: none;
}
#mortgage-affordability-tool-container .result-card {
background: #f8f9fa;
padding: 20px;
border-radius: 6px;
text-align: center;
margin-bottom: 20px;
}
#mortgage-affordability-tool-container .result-value {
font-size: 32px;
font-weight: 800;
color: #27ae60;
margin: 10px 0;
}
#mortgage-affordability-tool-container .result-label {
font-size: 14px;
color: #666;
text-transform: uppercase;
letter-spacing: 1px;
}
#mortgage-affordability-tool-container .breakdown {
font-size: 14px;
line-height: 1.6;
color: #666;
}
#mortgage-affordability-tool-container .error-msg {
color: #c0392b;
font-size: 14px;
margin-top: 5px;
display: none;
}
#mortgage-affordability-tool-container .grid-2 {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 20px;
}
@media (max-width: 600px) {
#mortgage-affordability-tool-container .grid-2 {
grid-template-columns: 1fr;
}
}
/* Article Styles */
#mortgage-affordability-tool-container .content-section h3 {
color: #2c3e50;
font-size: 20px;
margin-top: 30px;
border-bottom: 2px solid #eee;
padding-bottom: 10px;
}
#mortgage-affordability-tool-container .content-section p {
line-height: 1.7;
margin-bottom: 15px;
}
#mortgage-affordability-tool-container .content-section ul {
margin-bottom: 20px;
padding-left: 20px;
}
#mortgage-affordability-tool-container .content-section li {
margin-bottom: 8px;
line-height: 1.6;
}
function calculateAffordability() {
// 1. Get Inputs
var annualIncome = parseFloat(document.getElementById('annualIncome').value);
var monthlyDebt = parseFloat(document.getElementById('monthlyDebt').value) || 0;
var downPayment = parseFloat(document.getElementById('downPayment').value) || 0;
var interestRate = parseFloat(document.getElementById('interestRate').value);
var loanTermYears = parseFloat(document.getElementById('loanTerm').value);
var propertyTaxRate = parseFloat(document.getElementById('propertyTaxRate').value) || 1.2;
// 2. Validation
var errorDisplay = document.getElementById('errorDisplay');
if (isNaN(annualIncome) || isNaN(interestRate) || isNaN(loanTermYears) || annualIncome <= 0 || loanTermYears <= 0) {
errorDisplay.style.display = "block";
document.getElementById('resultsSection').style.display = "none";
return;
}
errorDisplay.style.display = "none";
// 3. Calculation Constants
var monthlyIncome = annualIncome / 12;
var insuranceRateAnnual = 0.005; // Estimate 0.5% for insurance
var taxRateMonthly = (propertyTaxRate / 100) / 12;
var insuranceRateMonthly = insuranceRateAnnual / 12;
// 4. Calculate Max Allowable Monthly Housing Payment (PITI)
// Front End: 28% of Gross Income
var maxPaymentFront = monthlyIncome * 0.28;
// Back End: 36% of Gross Income minus Monthly Debts
var maxPaymentBack = (monthlyIncome * 0.36) – monthlyDebt;
// The actual limit is the LOWER of the two
// If debts are very high, back end might be negative, so we floor at 0
if (maxPaymentBack < 0) maxPaymentBack = 0;
var maxAllowablePITI = Math.min(maxPaymentFront, maxPaymentBack);
// 5. Calculate Mortgage Factor
// M = P * ( r(1+r)^n ) / ( (1+r)^n – 1 )
// We need to reverse this to find P (Loan Amount) given M (portion of PITI available for P&I)
// PITI = (LoanAmount * MortgageFactor) + (HomePrice * TaxRateMonthly) + (HomePrice * InsRateMonthly)
// Note: LoanAmount = HomePrice – DownPayment
// Formula derivation:
// MaxPITI = ((Price – Down) * Factor) + (Price * TaxMonthly) + (Price * InsMonthly)
// MaxPITI = (Price * Factor) – (Down * Factor) + (Price * (Tax + Ins))
// MaxPITI + (Down * Factor) = Price * (Factor + Tax + Ins)
// Price = (MaxPITI + (Down * Factor)) / (Factor + Tax + Ins)
var monthlyRate = (interestRate / 100) / 12;
var numPayments = loanTermYears * 12;
var mortgageFactor = 0;
if (monthlyRate === 0) {
mortgageFactor = 1 / numPayments;
} else {
mortgageFactor = (monthlyRate * Math.pow(1 + monthlyRate, numPayments)) / (Math.pow(1 + monthlyRate, numPayments) – 1);
}
var combinedMonthlyTaxIns = taxRateMonthly + insuranceRateMonthly;
var maxHomePrice = (maxAllowablePITI + (downPayment * mortgageFactor)) / (mortgageFactor + combinedMonthlyTaxIns);
// Handle edge case where maxHomePrice is less than downpayment (unlikely math but possible with high debts)
if (maxHomePrice < downPayment) {
// Technically if PITI is 0, they can only afford the downpayment if no carrying costs,
// but carrying costs exist. Let's floor at downpayment or 0.
maxHomePrice = Math.max(0, downPayment);
}
// 6. Calculate Resulting Monthly Payment at that price
// This effectively recalculates PITI based on the derived Home Price to verify
var loanAmount = Math.max(0, maxHomePrice – downPayment);
var principalAndInterest = loanAmount * mortgageFactor;
var taxesAndIns = maxHomePrice * combinedMonthlyTaxIns;
var totalMonthlyPayment = principalAndInterest + taxesAndIns;
// 7. Display Results
// Format currency
var formatter = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD',
maximumFractionDigits: 0
});
document.getElementById('maxHomePrice').innerText = formatter.format(maxHomePrice);
document.getElementById('monthlyPayment').innerText = formatter.format(totalMonthlyPayment);
document.getElementById('frontEndLimit').innerText = formatter.format(maxPaymentFront);
document.getElementById('backEndLimit').innerText = formatter.format(maxPaymentBack < 0 ? 0 : maxPaymentBack);
document.getElementById('resultsSection').style.display = "block";
}
Mortgage Affordability Calculator
Please enter valid positive numbers for Income and Interest Rate.
Maximum Home Price
$0
Based on a monthly payment of $0
(Principal, Interest, Taxes & Insurance)
(Principal, Interest, Taxes & Insurance)
Front-End Ratio (28%)
Max housing payment allowed
$0
Max housing payment allowed
$0
Back-End Ratio (36%)
Max total debt allowed
$0
Max total debt allowed
$0
How Much House Can I Afford?
Determine your buying power with this Mortgage Affordability Calculator. Unlike simple loan calculators, this tool uses the "28/36 Rule"—the standard metric used by lenders to determine how much money they are willing to lend you.
Understanding the 28/36 Rule
Lenders look at two key ratios to ensure you don't borrow more than you can comfortably repay:
- The Front-End Ratio (28%): Housing costs (mortgage 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 + credit cards, student loans, car loans, etc.) should not exceed 36% of your gross monthly income.
This calculator determines the maximum home price by calculating both ratios and using the lower (more conservative) figure to ensure you stay within safe financial limits.
Key Factors Affecting Your Affordability
Several variables can significantly change how much home you can buy:
- Interest Rates: Even a 1% increase in interest rates can reduce your buying power by tens of thousands of dollars because more of your monthly payment goes toward interest rather than principal.
- 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).
- Debt Load: High monthly debts (like car payments or student loans) directly reduce the amount available for a mortgage under the Back-End Ratio.
How to Increase Your Home Buying Power
If the results are lower than expected, consider paying down high-interest consumer debt to lower your monthly obligations. Additionally, saving for a larger down payment not only increases equity immediately but also reduces the loan-to-value ratio, often securing better interest rates from lenders.