.mortgage-calculator-wrapper {
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
max-width: 800px;
margin: 0 auto;
background: #ffffff;
border: 1px solid #e2e8f0;
border-radius: 8px;
padding: 20px;
box-shadow: 0 4px 6px rgba(0,0,0,0.05);
}
.mortgage-calculator-wrapper h2 {
color: #2d3748;
margin-bottom: 20px;
text-align: center;
font-size: 24px;
}
.calc-grid {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 20px;
}
@media (max-width: 600px) {
.calc-grid {
grid-template-columns: 1fr;
}
}
.input-group {
margin-bottom: 15px;
}
.input-group label {
display: block;
margin-bottom: 5px;
font-weight: 600;
color: #4a5568;
font-size: 14px;
}
.input-wrapper {
position: relative;
display: flex;
align-items: center;
}
.input-prefix, .input-suffix {
background: #edf2f7;
padding: 10px 12px;
color: #4a5568;
border: 1px solid #cbd5e0;
font-size: 14px;
}
.input-prefix {
border-right: none;
border-radius: 4px 0 0 4px;
}
.input-suffix {
border-left: none;
border-radius: 0 4px 4px 0;
}
.calc-input {
width: 100%;
padding: 10px;
border: 1px solid #cbd5e0;
font-size: 16px;
color: #2d3748;
outline: none;
border-radius: 4px; /* Fallback */
}
.input-wrapper .calc-input {
border-radius: 0;
}
.input-wrapper .calc-input:first-child {
border-radius: 4px 0 0 4px;
}
.input-wrapper .calc-input:last-child {
border-radius: 0 4px 4px 0;
}
.calc-btn {
grid-column: 1 / -1;
background: #3182ce;
color: white;
border: none;
padding: 15px;
font-size: 18px;
font-weight: bold;
border-radius: 6px;
cursor: pointer;
transition: background 0.2s;
margin-top: 10px;
}
.calc-btn:hover {
background: #2c5282;
}
.results-section {
grid-column: 1 / -1;
background: #f7fafc;
border-radius: 8px;
padding: 20px;
margin-top: 20px;
display: none;
border: 1px solid #e2e8f0;
}
.main-result {
text-align: center;
margin-bottom: 20px;
padding-bottom: 20px;
border-bottom: 1px solid #e2e8f0;
}
.main-result-label {
font-size: 16px;
color: #718096;
margin-bottom: 5px;
}
.main-result-value {
font-size: 36px;
font-weight: 800;
color: #2b6cb0;
}
.breakdown-grid {
display: grid;
grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
gap: 15px;
}
.breakdown-item {
background: white;
padding: 10px;
border-radius: 4px;
border: 1px solid #edf2f7;
text-align: center;
}
.breakdown-label {
font-size: 12px;
color: #718096;
text-transform: uppercase;
letter-spacing: 0.5px;
}
.breakdown-value {
font-size: 18px;
font-weight: 600;
color: #2d3748;
margin-top: 5px;
}
.error-msg {
color: #e53e3e;
grid-column: 1 / -1;
text-align: center;
font-weight: bold;
display: none;
margin-top: 10px;
}
.seo-content {
margin-top: 40px;
line-height: 1.6;
color: #2d3748;
}
.seo-content h3 {
font-size: 20px;
margin-bottom: 15px;
color: #2c5282;
}
.seo-content p {
margin-bottom: 15px;
}
.seo-content ul {
margin-bottom: 15px;
padding-left: 20px;
}
.seo-content li {
margin-bottom: 8px;
}
function calculateMortgage() {
// 1. Get DOM elements
var homePriceInput = document.getElementById("homePrice");
var downPaymentInput = document.getElementById("downPayment");
var loanTermInput = document.getElementById("loanTerm");
var interestRateInput = document.getElementById("interestRate");
var propertyTaxInput = document.getElementById("propertyTax");
var homeInsuranceInput = document.getElementById("homeInsurance");
var hoaFeesInput = document.getElementById("hoaFees");
var errorMsg = document.getElementById("errorMsg");
var resultsSection = document.getElementById("resultsSection");
// 2. Parse values
var homePrice = parseFloat(homePriceInput.value);
var downPayment = parseFloat(downPaymentInput.value);
var loanTermYears = parseFloat(loanTermInput.value);
var annualRate = parseFloat(interestRateInput.value);
var annualTax = parseFloat(propertyTaxInput.value);
var annualInsurance = parseFloat(homeInsuranceInput.value);
var monthlyHoa = parseFloat(hoaFeesInput.value);
// 3. Validation
if (isNaN(homePrice) || isNaN(downPayment) || isNaN(loanTermYears) ||
isNaN(annualRate) || isNaN(annualTax) || isNaN(annualInsurance) ||
homePrice <= 0 || loanTermYears <= 0) {
errorMsg.style.display = "block";
resultsSection.style.display = "none";
return;
}
errorMsg.style.display = "none";
// 4. Calculation Logic
var principal = homePrice – downPayment;
// Handle 0 principal or negative equity
if (principal <= 0) {
principal = 0;
}
// Monthly interest rate
var monthlyRate = (annualRate / 100) / 12;
var numberOfPayments = loanTermYears * 12;
// Calculate Monthly Principal & Interest (P&I)
var monthlyPI = 0;
if (annualRate === 0) {
monthlyPI = principal / numberOfPayments;
} else {
// Formula: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
monthlyPI = principal * (monthlyRate * Math.pow(1 + monthlyRate, numberOfPayments)) / (Math.pow(1 + monthlyRate, numberOfPayments) – 1);
}
// Monthly Tax and Insurance
var monthlyTax = annualTax / 12;
var monthlyInsurance = annualInsurance / 12;
// Total Monthly Payment
var totalMonthly = monthlyPI + monthlyTax + monthlyInsurance + (isNaN(monthlyHoa) ? 0 : monthlyHoa);
// Total Loan Cost
var totalPaymentOverTerm = (monthlyPI * numberOfPayments);
var totalInterest = totalPaymentOverTerm – principal;
// Payoff Date
var today = new Date();
var payoffDateObj = new Date(today.setMonth(today.getMonth() + numberOfPayments));
var payoffMonth = payoffDateObj.toLocaleString('default', { month: 'short' });
var payoffYear = payoffDateObj.getFullYear();
var payoffString = payoffMonth + " " + payoffYear;
// 5. Update UI
document.getElementById("totalMonthlyPayment").textContent = formatMoney(totalMonthly);
document.getElementById("piPayment").textContent = formatMoney(monthlyPI);
document.getElementById("taxPayment").textContent = formatMoney(monthlyTax);
document.getElementById("insPayment").textContent = formatMoney(monthlyInsurance);
document.getElementById("totalLoanAmount").textContent = formatMoney(principal);
document.getElementById("totalInterest").textContent = formatMoney(totalInterest);
document.getElementById("payoffDate").textContent = payoffString;
resultsSection.style.display = "block";
}
function formatMoney(amount) {
return "$" + amount.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
}
Advanced Mortgage Payment Calculator
$
$
Years
%
$
$
$
Please enter valid positive numbers for all fields.
Estimated Monthly Payment
$0.00
Principal & Interest
$0.00
Property Tax
$0.00
Home Insurance
$0.00
Total Loan Amount
$0.00
Total Interest Cost
$0.00
Payoff Date
–
Understanding Your Mortgage Payment
Calculating your potential monthly mortgage payment is a crucial first step in the home buying process. This Advanced Mortgage Calculator goes beyond simple principal and interest calculations to give you a realistic view of your monthly housing costs, including taxes, insurance, and HOA fees.
Key Factors Affecting Your Mortgage
When you take out a home loan, your monthly payment is composed of several parts, often referred to as PITI (Principal, Interest, Taxes, and Insurance):
- Principal: The portion of your payment that goes toward paying down the original loan balance.
- Interest: The cost of borrowing money, determined by your interest rate. In the early years of a mortgage, the majority of your payment goes toward interest.
- Property Taxes: Taxes assessed by your local government, usually based on the value of the property. These are often held in an escrow account by your lender.
- Homeowners Insurance: Insurance that protects your home against damages. Lenders require this to protect the asset securing the loan.
How Interest Rates Impact Affordability
Even a small change in interest rates can significantly impact your monthly payment and the total cost of your loan. For example, on a $300,000 loan, a 1% increase in interest rate can increase your monthly payment by hundreds of dollars and your total interest paid over 30 years by tens of thousands.
Using This Calculator
To get the most accurate result, try to input exact figures for property taxes and insurance if you have them from a property listing. If you are putting down less than 20% of the home price, keep in mind that you may also need to pay Private Mortgage Insurance (PMI), though this calculator focuses on the standard carrying costs.