Amortization Schedule Calculator
body {
font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
line-height: 1.6;
margin: 0;
padding: 0;
background-color: #f8f9fa;
color: #333;
}
.loan-calc-container {
max-width: 900px;
margin: 30px auto;
padding: 30px;
background-color: #ffffff;
border-radius: 8px;
box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
border: 1px solid #e0e0e0;
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h1, h2 {
color: #004a99;
text-align: center;
margin-bottom: 20px;
}
.input-group {
margin-bottom: 20px;
padding: 15px;
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border-radius: 5px;
border: 1px solid #cce5ff;
display: flex;
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justify-content: space-between;
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.input-group label {
font-weight: bold;
margin-right: 10px;
flex-basis: 150px; /* Fixed width for labels */
flex-shrink: 0;
}
.input-group input[type="number"],
.input-group input[type="text"] {
flex-grow: 1;
padding: 10px;
border: 1px solid #ccc;
border-radius: 4px;
box-sizing: border-box;
min-width: 150px; /* Ensure minimum width on smaller screens */
}
.input-group input[type="number"]:focus,
.input-group input[type="text"]:focus {
border-color: #004a99;
outline: none;
box-shadow: 0 0 5px rgba(0, 74, 153, 0.5);
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button {
display: block;
width: 100%;
padding: 12px 20px;
background-color: #004a99;
color: white;
border: none;
border-radius: 5px;
font-size: 16px;
cursor: pointer;
transition: background-color 0.3s ease;
margin-top: 10px;
}
button:hover {
background-color: #003f85;
}
.result-section {
margin-top: 30px;
padding: 20px;
background-color: #d4edda;
border: 1px solid #28a745;
border-radius: 5px;
text-align: center;
}
.result-section h3 {
color: #28a745;
margin-top: 0;
}
#summaryResult p {
font-size: 1.2em;
margin: 10px 0;
}
#summaryResult .total-interest,
#summaryResult .total-paid {
font-weight: bold;
}
#summaryResult .total-interest {
color: #dc3545;
}
#summaryResult .total-paid {
color: #28a745;
}
#scheduleTable {
width: 100%;
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margin-top: 25px;
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}
#scheduleTable th, #scheduleTable td {
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#scheduleTable th {
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#scheduleTable tr:nth-child(even) {
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@media (max-width: 768px) {
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align-items: flex-start;
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.input-group label {
margin-bottom: 10px;
margin-right: 0;
flex-basis: auto;
}
.input-group input[type="number"],
.input-group input[type="text"] {
width: 100%;
min-width: auto;
}
.loan-calc-container {
margin: 15px;
padding: 20px;
}
#scheduleTable {
font-size: 0.8em;
}
#scheduleTable th, #scheduleTable td {
padding: 8px;
}
}
Amortization Schedule Calculator
Loan Summary
Monthly Payment:
Total Principal Paid:
Total Interest Paid:
Total Amount Paid:
Amortization Schedule
| Payment # |
Date |
Payment |
Principal |
Interest |
Balance |
Understanding Amortization Schedules
An amortization schedule is a table that details each periodic payment on an amortizing loan (like a mortgage, auto loan, or personal loan) over the life of the loan. Each payment is applied to both the principal balance and the interest accrued. As the principal balance decreases, the portion of the payment allocated to interest also decreases, while the portion allocated to principal increases.
How Amortization Works
The core principle behind an amortizing loan is that each payment is calculated to gradually pay down the debt over a set period. The formula for calculating the fixed periodic payment (M) is derived from the present value of an annuity formula:
M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1]
Where:
M = Periodic Payment (what you'll pay each period)P = Principal Loan Amount (the initial amount borrowed)i = Periodic Interest Rate (the annual interest rate divided by the number of payments per year)n = Total Number of Payments (the loan term in years multiplied by the number of payments per year)
Key Components of an Amortization Schedule
- Payment Number: The sequential number of the payment (e.g., 1st payment, 2nd payment).
- Date: The date on which the payment is due.
- Payment: The fixed total amount paid each period.
- Interest Paid: The portion of the payment that goes towards covering the interest accrued since the last payment. This is calculated as
Remaining Balance * Periodic Interest Rate.
- Principal Paid: The portion of the payment that reduces the outstanding loan balance. This is calculated as
Total Payment - Interest Paid.
- Remaining Balance: The outstanding amount of the loan after the payment has been applied. This is calculated as
Previous Balance - Principal Paid.
Why Use an Amortization Calculator?
- Budgeting: Predict your fixed loan payments accurately for effective financial planning.
- Loan Comparison: Easily compare different loan offers by seeing the total interest paid and payment structures.
- Extra Payments: Understand how making extra principal payments can significantly reduce the total interest paid and shorten the loan term.
- Financial Literacy: Gain a clearer understanding of how loans are repaid and the impact of interest over time.
Example Scenario
Let's consider a loan of $200,000 with an annual interest rate of 5% (0.05), a loan term of 30 years, and monthly payments (12 payments per year).
- Principal (P) = $200,000
- Annual Interest Rate = 5%
- Periodic Interest Rate (i) = 0.05 / 12 ≈ 0.00416667
- Loan Term = 30 years
- Total Payments (n) = 30 * 12 = 360
Using the formula, the monthly payment (M) would be approximately $1,073.64.
The first payment would allocate roughly $833.33 to principal and $239.70 to interest, leaving a balance of $199,166.67. As payments continue, the interest portion decreases and the principal portion increases, until the balance reaches $0.
function calculateAmortization() {
var loanAmount = parseFloat(document.getElementById("loanAmount").value);
var annualInterestRate = parseFloat(document.getElementById("annualInterestRate").value);
var loanTermYears = parseInt(document.getElementById("loanTermYears").value);
var paymentFrequency = parseInt(document.getElementById("paymentFrequency").value);
// Clear previous results and table
document.getElementById("summaryResult").style.display = "none";
document.getElementById("scheduleTableContainer").style.display = "none";
document.getElementById("scheduleBody").innerHTML = "";
// Input validation
if (isNaN(loanAmount) || loanAmount <= 0) {
alert("Please enter a valid loan amount.");
return;
}
if (isNaN(annualInterestRate) || annualInterestRate < 0) {
alert("Please enter a valid annual interest rate.");
return;
}
if (isNaN(loanTermYears) || loanTermYears <= 0) {
alert("Please enter a valid loan term in years.");
return;
}
if (isNaN(paymentFrequency) || paymentFrequency <= 0) {
alert("Please enter a valid payment frequency.");
return;
}
var periodicInterestRate = (annualInterestRate / 100) / paymentFrequency;
var totalPayments = loanTermYears * paymentFrequency;
var monthlyPayment = 0;
// Calculate monthly payment using the annuity formula
if (periodicInterestRate === 0) {
monthlyPayment = loanAmount / totalPayments;
} else {
monthlyPayment = loanAmount * (periodicInterestRate * Math.pow(1 + periodicInterestRate, totalPayments)) / (Math.pow(1 + periodicInterestRate, totalPayments) – 1);
}
// Round the monthly payment to two decimal places
monthlyPayment = Math.round(monthlyPayment * 100) / 100;
var totalPrincipalPaid = 0;
var totalInterestPaid = 0;
var remainingBalance = loanAmount;
var scheduleBody = document.getElementById("scheduleBody");
var today = new Date();
var currentDate = new Date(today.getFullYear(), today.getMonth(), today.getDate());
for (var i = 1; i <= totalPayments; i++) {
var interestForPeriod = Math.round(remainingBalance * periodicInterestRate * 100) / 100;
var principalForPeriod = monthlyPayment – interestForPeriod;
// Adjust last payment to ensure balance is exactly zero
if (i === totalPayments) {
principalForPeriod = remainingBalance;
interestForPeriod = monthlyPayment – principalForPeriod;
if (interestForPeriod < 0) interestForPeriod = 0; // Ensure interest isn't negative if payment slightly overshoots
monthlyPayment = principalForPeriod + interestForPeriod;
}
remainingBalance -= principalForPeriod;
// Ensure remaining balance doesn't go negative due to rounding
if (remainingBalance < 0) remainingBalance = 0;
totalInterestPaid += interestForPeriod;
totalPrincipalPaid += principalForPeriod; // This should closely match loanAmount, can be used as a check
// Format date for display
var paymentDate = new Date(currentDate);
// Basic date increment logic for schedule (assuming monthly for simplicity, can be adjusted)
paymentDate.setMonth(currentDate.getMonth() + i);
var formattedDate = (paymentDate.getMonth() + 1) + "/" + paymentDate.getDate() + "/" + paymentDate.getFullYear();
var row = scheduleBody.insertRow();
row.insertCell(0).textContent = i;
row.insertCell(1).textContent = formattedDate;
row.insertCell(2).textContent = monthlyPayment.toFixed(2);
row.insertCell(3).textContent = principalForPeriod.toFixed(2);
row.insertCell(4).textContent = interestForPeriod.toFixed(2);
row.insertCell(5).textContent = remainingBalance.toFixed(2);
}
var totalAmountPaid = totalPrincipalPaid + totalInterestPaid;
document.getElementById("monthlyPayment").textContent = monthlyPayment.toFixed(2);
document.getElementById("totalPrincipal").textContent = loanAmount.toFixed(2); // Should ideally match loanAmount
document.getElementById("totalInterest").textContent = totalInterestPaid.toFixed(2);
document.getElementById("totalAmountPaid").textContent = totalAmountPaid.toFixed(2);
document.getElementById("summaryResult").style.display = "block";
document.getElementById("scheduleTableContainer").style.display = "block";
}