BMI Calculator Using HTML , CSS & JavaScript With Source Code

BMI Calculator

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:

  1. 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).

  2. BMI Calculation: The application calculates the BMI using the formula: BMI = weight (kg) / (height (m))^2. The result is then displayed to the user.

  3. 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.

  4. 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.

  5. Attractive Layout Design: The user interface is visually appealing, featuring a modern and clean design to enhance the overall user experience.

  6. 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:

				
					


<!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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t.prototype={update:function(t){var e,n,a,i=this._settings,o=X(t,i);{if(h(this,o.length),!tt&&et)return H(i)?(e=i,n=this,o.forEach(function(t){-1!==kt.indexOf(t.tagName)&&F(t,e,n)}),void h(n,0)):(t=this._observer,i=o,t.disconnect(),a=t,void i.forEach(function(t){a.observe(t)}));this.loadAll(o)}},destroy:function(){this._observer&&this._observer.disconnect(),Q(this._settings).forEach(function(t){y(t)}),delete this._observer,delete this._settings,delete this.loadingCount,delete this.toLoadCount},loadAll:function(t){var e=this,n=this._settings;X(t,n).forEach(function(t){b(t,e),V(t,n,e)})},restoreAll:function(){var e=this._settings;Q(e).forEach(function(t){U(t,e)})}},t.load=function(t,e){e=i(e);V(t,e)},t.resetStatus=function(t){r(t)},Z&&function(t,e){if(e)if(e.length)for(var n,a=0;n=e[a];a+=1)o(t,n);else o(t,e)}(t,window.lazyLoadOptions),t});!function(e,t){"use strict";function a(){t.body.classList.add("litespeed_lazyloaded")}function n(){console.log("[LiteSpeed] Start Lazy Load 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litespeed_ui_events=["mouseover","click","keydown","wheel","touchmove","touchstart"];var urlCreator=window.URL||window.webkitURL;function litespeed_load_delayed_js_force(){console.log("[LiteSpeed] Start Load JS Delayed"),litespeed_ui_events.forEach(e=>{window.removeEventListener(e,litespeed_load_delayed_js_force,{passive:!0})}),document.querySelectorAll("iframe[data-litespeed-src]").forEach(e=>{e.setAttribute("src",e.getAttribute("data-litespeed-src"))}),"loading"==document.readyState?window.addEventListener("DOMContentLoaded",litespeed_load_delayed_js):litespeed_load_delayed_js()}litespeed_ui_events.forEach(e=>{window.addEventListener(e,litespeed_load_delayed_js_force,{passive:!0})});async function litespeed_load_delayed_js(){let t=[];for(var d in document.querySelectorAll('script[type="litespeed/javascript"]').forEach(e=>{t.push(e)}),t)await new Promise(e=>litespeed_load_one(t[d],e));document.dispatchEvent(new Event("DOMContentLiteSpeedLoaded")),window.dispatchEvent(new Event("DOMContentLiteSpeedLoaded"))}function litespeed_load_one(t,e){console.log("[LiteSpeed] Load ",t);var d=document.createElement("script");d.addEventListener("load",e),d.addEventListener("error",e),t.getAttributeNames().forEach(e=>{"type"!=e&&d.setAttribute("data-src"==e?"src":e,t.getAttribute(e))});let a=!(d.type="text/javascript");!d.src&&t.textContent&&(d.src=litespeed_inline2src(t.textContent),a=!0),t.after(d),t.remove(),a&&e()}function litespeed_inline2src(t){try{var d=urlCreator.createObjectURL(new Blob([t.replace(/^(?:<!--)?(.*?)(?:-->)?$/gm,"$1")],{type:"text/javascript"}))}catch(e){d="data:text/javascript;base64,"+btoa(t.replace(/^(?:<!--)?(.*?)(?:-->)?$/gm,"$1"))}return d}</script></body>
</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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