Build a Dynamic Mortgage Calculator with JavaScript

How to build a Mortgage Calculator using JavaScript

Are you interested in creating a practical Mortgage Calculator for your website? In this step-by-step guide, we’ll walk through the process of building a Mortgage Calculator using HTML, CSS, and JavaScript. This tool will allow users to calculate monthly mortgage payments based on the loan amount, interest rate, and loan tenure.

Introduction

A mortgage calculator is a financial tool designed to help individuals estimate their monthly mortgage payments based on key variables such as loan amount, interest rate, loan tenure, and sometimes additional factors like property taxes and insurance. It provides users with a quick and accurate computation of what their monthly mortgage payment would be, allowing them to plan and budget effectively.

Key Components of a Mortgage Calculator

A mortgage calculator has the following key components:

  1. Loan Amount: The total amount borrowed from a lender to purchase a home.
  2. Interest Rate: The annual interest rate applied to the loan.
  3. Loan Tenure: The number of years over which the loan is repaid.
Mortgage Calculator

Prerequisites

Before diving into the code, make sure you have a basic understanding of HTMLCSS, and JavaScript. Ensure you have a text editor like Visual Studio Code or Sublime Text installed for a seamless coding experience.

Setting Up the HTML Structure for Mortgage Calculator

Let’s start by creating the HTML structure for our calculator. Open your preferred code editor such as Visual Studio Code or Sublime Text and create a new HTML file say index.html:

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <link rel="stylesheet" href="styles.css">
    <title>Mortgage Calculator</title>
</head>
<body>
     <div class="calculator">
        <h1>Mortgage Calculator</h1>

        <label for="loanAmount">Loan Amount:</label>
        <input type="number" id="loanAmount" required>

        <br/>

        <label for="interestRate">Interest Rate (%):</label>
        <input type="number" id="interestRate" step="0.1" required>

        <br/>

        <label for="loanTenure">Loan Tenure (years):</label>
        <input type="number" id="loanTenure" required>

        <br/>

        <button onclick="calculateMortgage()">Calculate</button>

        <hr />

        <h4 id="result">Monthly Payment: </h4>
    </div>

    <script src="script.js"></script>
</body>
</html>

The above HTML code is the foundation of the calculator. You can modify the HTML based on the framework you are using.

Styling with CSS

Enhance the visual appeal of your calculator with some CSS. Create a new file named styles.css:

body {
    font-family: 'Arial', sans-serif;
    display: flex;
    align-items: center;
    justify-content: center;
    height: 100vh;
    margin: 0;
    font-size: 17px;
    background: #fafafa;
}
h1 {
    margin: 5px 0 15px 0;
    text-align: center;
    text-transform: uppercase;
    font-size: 20px;
    letter-spacing: 1px
}
.calculator {
    width: 400px;
    padding: 20px;
    border: 1px solid #ccc;
    border-radius: 5px;
    background: #fff;
}
label, input, button {
    margin: 10px 0;
}
input {
    display: block;
    width: calc(100% - 20px);
    padding: 10px;
}
button {
    background-color: #000;
    color: #fff;
    outline: 0;
    border: 0;
    padding: 10px 15px;
    cursor: pointer;
    font-size: 16px;
    margin: 0 auto; 
    border-radius: 5px;
    margin-bottom: 5px;
}
hr {
    margin: 15px 0;
}
h4 {
    margin-bottom: 0;
}

This will create a very basic layout of the calculator. Feel free to modify the stylings as per your design requirements.

Implementing JavaScript Functionality

Now, let’s add the JavaScript code to make our mortgage calculator functional. Create a new file named script.js.

The script has 2 parts; taking input from the user and processing the input data to get the results. The calculateMortgage() will process the input values and return the monthly payment.

// JavaScript Functionality

// DOM elements
const loanAmountInput = document.getElementById('loanAmount');
const interestRateInput = document.getElementById('interestRate');
const loanTenureInput = document.getElementById('loanTenure');
const calculateButton = document.getElementById('calculateButton');
const resultOutput = document.getElementById('result');

// Calculate mortgage function
function calculateMortgage() {
    const loanAmount = parseFloat(loanAmountInput.value);
    const interestRate = parseFloat(interestRateInput.value) / 100 / 12;
    const loanTenureMonths = parseFloat(loanTenureInput.value) * 12;

    const monthlyPayment = (loanAmount * interestRate) / (1 - Math.pow(1 + interestRate, -loanTenureMonths));

    // Display result
    resultOutput.innerText = `Monthly Payment: $${monthlyPayment.toFixed(2)}`;
}

Click here to visit a more advanced mortgage calculator.

Conclusion

Congratulations! You’ve just built a mortgage calculator using HTML, CSS, and JavaScript. Users can now input their loan details and get an estimate of their monthly mortgage payments.

Feel free to customize the styling and functionality further to suit your website’s design. This hands-on project is an excellent way to enhance your web programming skills.

Remember to test your calculator thoroughly and consider adding error handling for a better user experience. Happy coding!

Related Posts