Compound Interest Calculator
Understand how your investments can grow over time with the power of compounding. Compound interest is interest calculated on the initial principal, which also includes all of the accumulated interest from previous periods. It's often referred to as "interest on interest."
function calculateCompoundInterest() {
var principal = parseFloat(document.getElementById("principal").value);
var annualRate = parseFloat(document.getElementById("annualRate").value);
var time = parseFloat(document.getElementById("time").value);
var compoundingFrequency = parseInt(document.getElementById("compoundingFrequency").value);
var resultDiv = document.getElementById("result");
resultDiv.innerHTML = ""; // Clear previous results
if (isNaN(principal) || isNaN(annualRate) || isNaN(time) || isNaN(compoundingFrequency)) {
resultDiv.innerHTML = "Please enter valid numbers for all fields.";
return;
}
if (principal <= 0 || annualRate < 0 || time <= 0 || compoundingFrequency <= 0) {
resultDiv.innerHTML = "Please enter positive values for principal, time, and compounding frequency, and a non-negative value for the annual rate.";
return;
}
var ratePerPeriod = annualRate / 100 / compoundingFrequency;
var numberOfPeriods = time * compoundingFrequency;
var futureValue = principal * Math.pow((1 + ratePerPeriod), numberOfPeriods);
var totalInterestEarned = futureValue – principal;
resultDiv.innerHTML = `
Results:
Final Amount: $${futureValue.toFixed(2)}
Total Interest Earned: $${totalInterestEarned.toFixed(2)}
`;
}
#compound-interest-calculator {
font-family: sans-serif;
max-width: 600px;
margin: 20px auto;
padding: 20px;
border: 1px solid #ddd;
border-radius: 8px;
background-color: #f9f9f9;
}
#compound-interest-calculator h2 {
text-align: center;
color: #333;
margin-bottom: 20px;
}
.calculator-inputs {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 15px;
margin-bottom: 20px;
}
.input-group {
display: flex;
flex-direction: column;
}
.input-group label {
margin-bottom: 5px;
font-weight: bold;
color: #555;
}
.input-group input[type="number"],
.input-group select {
padding: 10px;
border: 1px solid #ccc;
border-radius: 4px;
font-size: 1em;
}
#compound-interest-calculator button {
grid-column: 1 / -1; /* Span across both columns */
padding: 12px 20px;
background-color: #4CAF50;
color: white;
border: none;
border-radius: 4px;
cursor: pointer;
font-size: 1.1em;
transition: background-color 0.3s ease;
}
#compound-interest-calculator button:hover {
background-color: #45a049;
}
.calculator-result {
margin-top: 20px;
padding: 15px;
background-color: #e9e9e9;
border: 1px solid #ccc;
border-radius: 4px;
}
.calculator-result h3 {
margin-top: 0;
color: #333;
}
.calculator-result p {
margin: 5px 0;
font-size: 1.1em;
}