Calculate the potential interest you'll pay on your credit card balance.
Estimated Interest Paid Over Time
$0.00
Understanding Credit Card Interest
Credit cards are a convenient financial tool, but they can become expensive if you carry a balance. The interest charged on credit cards is typically calculated using a daily periodic rate applied to your average daily balance. Understanding how this interest accrues is crucial for managing your debt effectively and minimizing the total amount you pay.
How Credit Card Interest Works
Credit card interest is calculated based on three main components:
Your Balance: The amount of money you owe on the card.
Your Annual Percentage Rate (APR): This is the yearly interest rate. Credit card companies divide this by 365 (or sometimes 360) to get a daily periodic rate.
The Number of Days in the Billing Cycle: The daily rate is applied to your average daily balance for the days in your billing cycle.
The Calculation Formula
This calculator simplifies the process to give you an estimate. The core idea is to simulate month-by-month how your balance changes. For each month:
Calculate Daily Rate: Annual Rate / 100 / 365
Calculate Monthly Interest: Balance * Daily Rate * Days in Month
New Balance: Balance + Monthly Interest – Monthly Payment
The calculator iterates this process until the balance is paid off, accumulating the total interest paid.
Why Use This Calculator?
This tool helps you:
Visualize the Cost of Debt: See exactly how much extra you're paying in interest by carrying a balance.
Evaluate Payment Strategies: Understand the impact of making larger monthly payments. Even a small increase can significantly reduce the time it takes to pay off debt and the total interest paid.
Budgeting: Factor potential interest charges into your monthly budget.
Debt Management: Plan your debt repayment strategy and stay motivated by seeing progress.
Tips for Minimizing Credit Card Interest:
Pay Your Balance in Full: The best way to avoid interest is to pay your statement balance by the due date each month.
Make More Than the Minimum Payment: Even small additional payments can make a big difference over time.
Consider Balance Transfers: If you have a high-interest balance, transferring it to a card with a 0% introductory APR can save you money (be mindful of transfer fees and the rate after the intro period).
Avoid Cash Advances: These typically come with higher interest rates and fees, and interest starts accruing immediately.
Use this calculator as a guide to make informed financial decisions and take control of your credit card debt.
function calculateInterest() {
var balance = parseFloat(document.getElementById("balance").value);
var annualRate = parseFloat(document.getElementById("annualRate").value);
var monthlyPayment = parseFloat(document.getElementById("payment").value);
var resultDiv = document.getElementById("result");
var totalInterestDisplay = document.getElementById("totalInterestDisplay");
var yearsToPayDisplay = document.getElementById("yearsToPayDisplay");
if (isNaN(balance) || isNaN(annualRate) || isNaN(monthlyPayment) || balance <= 0 || annualRate < 0 || monthlyPayment <= 0) {
alert("Please enter valid positive numbers for all fields.");
resultDiv.style.display = 'none';
return;
}
if (monthlyPayment 0) {
var monthlyInterest = currentBalance * dailyRate * daysInMonth;
if (monthlyInterest >= currentBalance && months > 0) { // Prevent infinite loop if payment barely covers interest
monthlyInterest = currentBalance; // Pay off remaining balance
monthlyPayment = currentBalance; // Adjust payment to match remaining balance
}
// Ensure payment covers interest and principal
var actualPayment = Math.min(monthlyPayment, currentBalance + monthlyInterest);
var principalPaid = actualPayment – monthlyInterest;
if (principalPaid < 0) { // Edge case where payment only covers interest
principalPaid = 0;
monthlyInterest = actualPayment; // Entire payment goes to interest if it can't even cover that
}
totalInterestPaid += monthlyInterest;
currentBalance -= principalPaid;
if (currentBalance 10000) { // Safety break for extremely long calculations
alert("Calculation is taking too long. Please check your inputs.");
resultDiv.style.display = 'none';
return;
}
}
var years = Math.floor(months / 12);
var remainingMonths = months % 12;
var timeToPayString = "";
if (years > 0) {
timeToPayString += years + " year" + (years > 1 ? "s" : "");
}
if (remainingMonths > 0) {
if (years > 0) timeToPayString += ", ";
timeToPayString += remainingMonths + " month" + (remainingMonths > 1 ? "s" : "");
}
if (months === 0) { // Handles case where balance is already 0 or payment is extremely high
timeToPayString = "Paid off immediately";
totalInterestPaid = 0;
}
totalInterestDisplay.textContent = "$" + totalInterestPaid.toFixed(2);
yearsToPayDisplay.textContent = "Estimated time to pay off: " + timeToPayString;
resultDiv.style.display = 'block';
}