Build a Calculator in JavaScript in Just 5 Minutes (Copy & Paste Project!)
Learn how to build a stylish calculator using HTML, CSS, and JavaScript.
Copy the code, paste it, and create a working calculator in just 10 minutes — perfect for IT students and beginners.
Project Overview
| Item | Detail |
| Project Name | Modern Calculator UI |
| Languages Used | HTML, CSS, JavaScript |
| Time Required | 10 minutes |
| Level | Beginner |
| Use Case | Mini project, resume, college submission |
Why This Calculator Project is for IT Students
Most students struggle to build working projects quickly. This one solves that problem — you can copy the code, paste it into your editor, and see results instantly.
Tools You Need
- Any Code Editor (VS Code, Sublime, Notepad++)
- Browser (Chrome)
How to Build the Calculator
- Copy the full code below
- Paste it into a file named
calculator.html - Double-click the file to open it in your browser. You’re done!
Copy-Paste Code: Modern Calculator Project
The code below includes HTML, CSS, and JavaScript in one file.
Paste this code into your file (calculator.html) and run it instantly.
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0"/>
<title>Modern Calculator</title>
<style>
* {
box-sizing: border-box;
}
body {
font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
background: linear-gradient(to right, #0f2027, #203a43, #2c5364);
display: flex;
justify-content: center;
align-items: center;
height: 100vh;
margin: 0;
}
.calculator {
background: rgba(255, 255, 255, 0.05);
backdrop-filter: blur(10px);
border: 1px solid rgba(255, 255, 255, 0.1);
border-radius: 20px;
padding: 30px;
width: 320px;
box-shadow: 0 8px 32px rgba(0, 0, 0, 0.2);
}
#result {
width: 100%;
padding: 20px;
font-size: 2em;
text-align: right;
border: none;
border-radius: 15px;
margin-bottom: 20px;
background: rgba(255, 255, 255, 0.15);
color: #fff;
}
.buttons {
display: grid;
grid-template-columns: repeat(4, 1fr);
gap: 15px;
}
button {
padding: 20px;
font-size: 1.4em;
border: none;
border-radius: 15px;
background: rgba(255, 255, 255, 0.1);
color: white;
cursor: pointer;
transition: all 0.3s ease;
}
button:hover {
background: rgba(255, 255, 255, 0.3);
transform: scale(1.05);
}
button:active {
transform: scale(0.95);
}
::placeholder {
color: #ccc;
}
</style>
</head>
<body>
<div class="calculator">
<input type="text" id="result" placeholder="0" disabled />
<div class="buttons">
<button onclick="clearResult()">C</button>
<button onclick="backspace()">←</button>
<button onclick="appendValue('/')">/</button>
<button onclick="appendValue('*')">*</button>
<button onclick="appendValue('7')">7</button>
<button onclick="appendValue('8')">8</button>
<button onclick="appendValue('9')">9</button>
<button onclick="appendValue('-')">-</button>
<button onclick="appendValue('4')">4</button>
<button onclick="appendValue('5')">5</button>
<button onclick="appendValue('6')">6</button>
<button onclick="appendValue('+')">+</button>
<button onclick="appendValue('1')">1</button>
<button onclick="appendValue('2')">2</button>
<button onclick="appendValue('3')">3</button>
<button onclick="calculate()">=</button>
<button onclick="appendValue('0')">0</button>
<button onclick="appendValue('.')">.</button>
</div>
</div>
<script>
const result = document.getElementById('result');
function appendValue(value) {
result.value += value;
}
function clearResult() {
result.value = '';
}
function backspace() {
result.value = result.value.slice(0, -1);
}
function calculate() {
try {
result.value = eval(result.value);
} catch (err) {
result.value = 'Error';
}
}
</script>
</body>
</html>
What This Calculator Can Do
- Add (+)
- Subtract (-)
- Multiply (*)
- Divide (/)
- Clear & backspace option (<-)
- Looks modern and clean with rounded buttons and hover effects
Output Screenshot
Conclusion
This 10-minute JavaScript calculator project is perfect if:
- You’re a BCA or CSE student looking for a quick project
- You want to add to your portfolio
- You have a viva, an assignment, or need to show a demo
FAQs
Can I build a calculator using just HTML, CSS, and JavaScript?
Yes, this project uses only HTML, CSS, and JavaScript—no libraries or frameworks. It’s simple and perfect for beginners.
Can I run this calculator without installing anything?
Yes! You don’t need to install any software. Just paste the code into a text editor, save the file with a .html extension, and double-click it to open in your browser.
Is this calculator responsive on mobile?
Yes. The design uses CSS that adapts to different screen sizes. This project works well on mobile, tablets, and desktops.
