BMI Calculator Using HTML , CSS & JavaScript With Source Code

Introduction:

The Body Mass Index (BMI) calculator is a web application designed to help users calculate their BMI based on their height and weight. BMI is a measure of body fat based on an individual’s weight in relation to their height. This calculator provides a convenient way for users to assess their body composition and determine if they are underweight, normal weight, overweight, or obese according to standard BMI categories.

Key Features:

User Input: The calculator allows users to enter their height and weight in metric units (centimeters and kilograms) or imperial units (feet, inches, and pounds).
BMI Calculation: The application calculates the BMI using the formula: BMI = weight (kg) / (height (m))^2. The result is then displayed to the user.
BMI Categories: The calculated BMI is categorized into different ranges such as underweight, normal weight, overweight, and obese. These categories provide users with an understanding of their current body composition.
Responsive Design: The web application is designed to be responsive, adapting to different screen sizes and devices, ensuring optimal user experience across desktop, tablet, and mobile devices.
Attractive Layout Design: The user interface is visually appealing, featuring a modern and clean design to enhance the overall user experience.
Background Animation: The application incorporates a background animation to add an element of visual interest and engagement, making the user experience more enjoyable.

Source Code :

HTML:

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<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>BMI Calculator</title>
  <link data-asynced="1" as="style" onload="this.onload=null;this.rel='stylesheet'"  rel="preload" href="style.css">
</head>
<body>
  <div class="container">
    <h1>BMI Calculator</h1>
    <div class="input-container">
      <label for="height">Height:</label>
      <input type="number" id="height" placeholder="Height (cm)">
    </div>
    <div class="input-container">
      <label for="weight">Weight:</label>
      <input type="number" id="weight" placeholder="Weight (kg)">
    </div>
    <button onclick="calculateBMI()">Calculate</button>
    <div id="result"></div>
  </div> <script type="litespeed/javascript" data-src="script.js"></script> <script data-no-optimize="1">!function(t,e){"object"==typeof exports&&"undefined"!=typeof module?module.exports=e():"function"==typeof define&&define.amd?define(e):(t="undefined"!=typeof globalThis?globalThis:t||self).LazyLoad=e()}(this,function(){"use strict";function e(){return(e=Object.assign||function(t){for(var e=1;e<arguments.length;e++){var n,a=arguments[e];for(n in a)Object.prototype.hasOwnProperty.call(a,n)&&(t[n]=a[n])}return t}).apply(this,arguments)}function i(t){return e({},it,t)}function o(t,e){var n,a="LazyLoad::Initialized",i=new t(e);try{n=new CustomEvent(a,{detail:{instance:i}})}catch(t){(n=document.createEvent("CustomEvent")).initCustomEvent(a,!1,!1,{instance:i})}window.dispatchEvent(n)}function l(t,e){return t.getAttribute(gt+e)}function c(t){return l(t,bt)}function s(t,e){return function(t,e,n){e=gt+e;null!==n?t.setAttribute(e,n):t.removeAttribute(e)}(t,bt,e)}function r(t){return s(t,null),0}function u(t){return null===c(t)}function d(t){return c(t)===vt}function f(t,e,n,a){t&&(void 0===a?void 0===n?t(e):t(e,n):t(e,n,a))}function _(t,e){nt?t.classList.add(e):t.className+=(t.className?" 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</html>

CSS (style.css):

				
					/* @codewithcurious.com */

body {
  background-color: #f2f2f2;
  font-family: Arial, sans-serif;
  margin: 0;
  padding: 0;
}

.container {
  max-width: 400px;
  margin: 50px auto;
  padding: 20px;
  background-color: #fff;
  border-radius: 5px;
  box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
  text-align: center;
}

h1 {
  color: #333;
}

.input-container {
  margin-bottom: 10px;
  text-align: left;
}

input[type="number"] {
  width: 100%;
  padding: 10px;
  border: 1px solid #ccc;
  border-radius: 5px;
  box-sizing: border-box;
}

button {
  background-color: #4caf50;
  color: #fff;
  border: none;
  padding: 10px 20px;
  border-radius: 5px;
  cursor: pointer;
}

#result {
  margin-top: 20px;
  font-weight: bold;
}
/* @codewithcurious.com */

body {
  background-color: #f2f2f2;
  font-family: Arial, sans-serif;
  margin: 0;
  padding: 0;
}

.container {
  max-width: 400px;
  margin: 50px auto;
  padding: 20px;
  background-color: #fff;
  border-radius: 5px;
  box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
  text-align: center;
}

h1 {
  color: #333;
}

.input-container {
  margin-bottom: 10px;
  text-align: left;
}

input[type="number"] {
  width: 100%;
  padding: 10px;
  border: 1px solid #ccc;
  border-radius: 5px;
  box-sizing: border-box;
}

button {
  background-color: #4caf50;
  color: #fff;
  border: none;
  padding: 10px 20px;
  border-radius: 5px;
  cursor: pointer;
}

#result {
  margin-top: 20px;
  font-weight: bold;
}

JavaScript (script.js):

				
					//@codewithcurious.com

function calculateBMI() {
  var heightInput = document.getElementById("height");
  var weightInput = document.getElementById("weight");
  var resultDiv = document.getElementById("result");

  var height = parseFloat(heightInput.value);
  var weight = parseFloat(weightInput.value);

  if (isNaN(height) || isNaN(weight)) {
    resultDiv.innerHTML = "Please enter valid height and weight.";
    return;
  }

  var bmi = weight / ((height / 100) ** 2);
  var category = "";

  if (bmi < 18.5) {
    category = "Underweight";
  } else if (bmi < 25) {
    category = "Normal weight";
  } else if (bmi < 30) {
    category = "Overweight";
  } else {
    category = "Obese";
  }

  resultDiv.innerHTML = "Your BMI is " + bmi.toFixed(2) + " (" + category + ")";
}
//@codewithcurious.com

function calculateBMI() {
  var heightInput = document.getElementById("height");
  var weightInput = document.getElementById("weight");
  var resultDiv = document.getElementById("result");

  var height = parseFloat(heightInput.value);
  var weight = parseFloat(weightInput.value);

  if (isNaN(height) || isNaN(weight)) {
    resultDiv.innerHTML = "Please enter valid height and weight.";
    return;
  }

  var bmi = weight / ((height / 100) ** 2);
  var category = "";

  if (bmi < 18.5) {
    category = "Underweight";
  } else if (bmi < 25) {
    category = "Normal weight";
  } else if (bmi < 30) {
    category = "Overweight";
  } else {
    category = "Obese";
  }

  resultDiv.innerHTML = "Your BMI is " + bmi.toFixed(2) + " (" + category + ")";
}

Output:

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