.calculator-wrapper {
max-width: 800px;
margin: 0 auto;
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
color: #333;
line-height: 1.6;
}
.calc-container {
background: #f9f9f9;
border: 1px solid #e0e0e0;
border-radius: 8px;
padding: 25px;
box-shadow: 0 4px 6px rgba(0,0,0,0.05);
margin-bottom: 40px;
}
.calc-title {
text-align: center;
color: #2c3e50;
margin-bottom: 25px;
font-size: 24px;
font-weight: 700;
}
.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: 8px;
font-weight: 600;
font-size: 14px;
color: #555;
}
.input-group input {
width: 100%;
padding: 10px;
border: 1px solid #ccc;
border-radius: 4px;
font-size: 16px;
box-sizing: border-box;
}
.input-group input:focus {
border-color: #0073aa;
outline: none;
box-shadow: 0 0 0 2px rgba(0,115,170,0.2);
}
.calc-btn {
grid-column: 1 / -1;
background-color: #0073aa;
color: white;
border: none;
padding: 12px 20px;
font-size: 18px;
border-radius: 4px;
cursor: pointer;
width: 100%;
font-weight: bold;
transition: background-color 0.3s;
margin-top: 10px;
}
.calc-btn:hover {
background-color: #005177;
}
.results-box {
grid-column: 1 / -1;
background-color: #fff;
border: 1px solid #ddd;
border-radius: 4px;
padding: 20px;
margin-top: 20px;
display: none;
}
.result-row {
display: flex;
justify-content: space-between;
margin-bottom: 10px;
padding-bottom: 10px;
border-bottom: 1px solid #eee;
}
.result-row:last-child {
border-bottom: none;
margin-bottom: 0;
padding-bottom: 0;
}
.result-label {
font-weight: 600;
color: #555;
}
.result-value {
font-weight: 700;
color: #2c3e50;
}
.total-payment {
font-size: 20px;
color: #27ae60;
}
.calc-content {
margin-top: 40px;
}
.calc-content h2 {
color: #2c3e50;
font-size: 22px;
margin-top: 30px;
margin-bottom: 15px;
border-bottom: 2px solid #eee;
padding-bottom: 10px;
}
.calc-content h3 {
color: #444;
font-size: 18px;
margin-top: 20px;
margin-bottom: 10px;
}
.calc-content p {
margin-bottom: 15px;
color: #666;
}
.calc-content ul {
margin-bottom: 15px;
padding-left: 20px;
color: #666;
}
.calc-content li {
margin-bottom: 8px;
}
.error-msg {
color: #d63031;
text-align: center;
margin-top: 10px;
font-weight: bold;
display: none;
}
function calculateMortgage() {
// Get Input Values
var homePrice = parseFloat(document.getElementById("mortgageHomePrice").value);
var downPayment = parseFloat(document.getElementById("mortgageDownPayment").value);
var interestRate = parseFloat(document.getElementById("mortgageInterestRate").value);
var loanTermYears = parseFloat(document.getElementById("mortgageLoanTerm").value);
var annualTax = parseFloat(document.getElementById("mortgagePropertyTax").value);
var annualInsurance = parseFloat(document.getElementById("mortgageInsurance").value);
// Error Handling Element
var errorMsg = document.getElementById("mortgageError");
var resultBox = document.getElementById("mortgageResult");
// Validation
if (isNaN(homePrice) || isNaN(downPayment) || isNaN(interestRate) ||
isNaN(loanTermYears) || isNaN(annualTax) || isNaN(annualInsurance) ||
homePrice < 0 || downPayment < 0 || interestRate < 0 || loanTermYears <= 0) {
errorMsg.style.display = "block";
resultBox.style.display = "none";
return;
} else {
errorMsg.style.display = "none";
}
// Calculation Logic
var loanAmount = homePrice – downPayment;
// Handle case where down payment is greater than home price
if (loanAmount < 0) {
loanAmount = 0;
}
var monthlyInterestRate = (interestRate / 100) / 12;
var numberOfPayments = loanTermYears * 12;
var monthlyPrincipalInterest = 0;
// If interest rate is 0, just divide loan by months
if (interestRate === 0) {
monthlyPrincipalInterest = loanAmount / numberOfPayments;
} else {
// Amortization Formula: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
var mathPower = Math.pow(1 + monthlyInterestRate, numberOfPayments);
monthlyPrincipalInterest = loanAmount * (monthlyInterestRate * mathPower) / (mathPower – 1);
}
// Tax and Insurance Monthly
var monthlyTax = annualTax / 12;
var monthlyInsurance = annualInsurance / 12;
var monthlyTaxInsTotal = monthlyTax + monthlyInsurance;
// Total Monthly Payment
var totalMonthlyPayment = monthlyPrincipalInterest + monthlyTaxInsTotal;
// Update DOM
document.getElementById("resPrincipalInterest").innerHTML = "$" + monthlyPrincipalInterest.toFixed(2).replace(/\B(?=(\d{3})+(?!\d))/g, ",");
document.getElementById("resTaxIns").innerHTML = "$" + monthlyTaxInsTotal.toFixed(2).replace(/\B(?=(\d{3})+(?!\d))/g, ",");
document.getElementById("resLoanAmount").innerHTML = "$" + loanAmount.toFixed(2).replace(/\B(?=(\d{3})+(?!\d))/g, ",");
document.getElementById("resTotalMonthly").innerHTML = "$" + totalMonthlyPayment.toFixed(2).replace(/\B(?=(\d{3})+(?!\d))/g, ",");
// Show Results
resultBox.style.display = "block";
}
Mortgage Payment Calculator
Please enter valid positive numbers for all fields.
Principal & Interest:
$0.00
Monthly Tax & Insurance:
$0.00
Loan Amount:
$0.00
Total Monthly Payment:
$0.00
Understanding Your Mortgage Payments
Purchasing a home is one of the most significant financial decisions you will make. This Mortgage Payment Calculator helps you estimate your monthly housing costs by factoring in the loan principal, interest, property taxes, and homeowners insurance (PITI). Understanding these components is crucial for budgeting effectively.
How Mortgage Payments Are Calculated
Your monthly mortgage payment is primarily composed of four parts:
- Principal: The portion of your payment that goes toward paying down the original amount you borrowed.
- Interest: The cost of borrowing money, paid to the lender. In the early years of a mortgage, a larger portion of your payment goes toward interest.
- Taxes: Property taxes charged by your local government, usually collected by the lender and held in escrow.
- Insurance: Homeowners insurance to protect against damage, also typically paid via escrow.
Impact of Down Payment and Interest Rates
Two major factors influencing your monthly payment are the down payment and the interest rate.
The Down Payment
Putting more money down reduces the total loan amount, which lowers your monthly principal and interest payment. Additionally, if you put down at least 20% of the home's value, you typically avoid paying Private Mortgage Insurance (PMI), further reducing your monthly costs.
Interest Rates
Even a small difference in interest rates can have a massive impact over the life of a 30-year loan. For example, on a $300,000 loan, a 1% difference in interest rate can change your monthly payment by hundreds of dollars and your total interest paid by tens of thousands.
Using This Calculator for Budgeting
To get the most accurate estimate:
- Home Price: Enter the listing price or your offer price.
- Down Payment: Enter the cash amount you plan to pay upfront.
- Interest Rate: Check current market rates for your credit score profile.
- Taxes & Insurance: Look up the property's tax history on real estate listing sites (like Zillow or Redfin) to get a realistic annual figure.
Use this tool to experiment with different home prices and down payment amounts to find a monthly payment that fits comfortably within your budget.