# Calculate Compound Interest In Javascript

In this article, We will show you the programs to calculate compound interest in javascript. At last, we’ll also make a browser-based calculator for the compound interest. So let’s get started.

## What is Compound Interest:

Compound interest is a concept in finance that states that interest can be added to the principal sum invested so that the total amount grows at a faster rate than simple interest. It is actually interest on the interest that accumulates and grows exponentially over time.

Total Amount: A = P(1 + R/100)^T
Compound Interest: CI = A – P
Where P: principle amount, T: time, and R: Interest rate
For example, if you borrow \$20000 for three years at an annual compounded interest rate of 6%, you will pay the interest of \$3,820.32 and \$23,820.32 in the total.

## Program to calculate compound interest in javascript

Let’s create a program to calculate compound interest in javascript.

``````// Function to calculate compound interest in javascript
function compoundInterest(p, r, t) {
const total = p * Math.pow((1 + r / 100), t);
const interest = total - p;
return {
total: parseFloat(total.toFixed(2)),
interest: parseFloat(interest.toFixed(2))
}
}

console.log(compoundInterest(10000, 10, 3))
``````

### Result:

``{total: 13310, interest: 3310}``

### Code Explanation:

• First, we create a function named ‘compoundInterest’ that takes principle, rate of interest, and time as arguments.
• Then we calculate the total compounded amount and interest.
• Then we return the javascript object with the values converted rounded to 2 decimal places. (Note: toFixed() converts the output to a string, so we had to use parseFloat function to convert string to float).

## Create a browser-based compound interest calculator

Now it’s time to create the browser-based compound interest calculator with the three input number fields (Principle, Rate of interest, Time in Years) and a button. The total compounded amount and interest will be shown on the screen with a button click. Here is the code for that.

``````<html>
<body>
<input type="number" placeholder="Principle amount" id="p">
<input type="number" placeholder="Rate of interest" id="r">
<input type="number" placeholder="Time" id="t">
<button id="c">Calculate Compount Interst</button>
<p id="d"></p>

<script>
function compoundInterest(p, r, t) {
const total = p * Math.pow((1 + r / 100), t);
const interest = total - p;
return {
total: parseFloat(total.toFixed(2)),
interest: parseFloat(interest.toFixed(2))
}
}

function render() {
const t = document.querySelector("#t").value;
const p = document.querySelector("#p").value;
const r = document.querySelector("#r").value;

const v = compoundInterest(p, r, t);
const result = `Interest: \$\${v.interest}, Total Amt: \$\${v.total}`;
document.querySelector("#d").innerHTML = result
} 