.bmi-calculator-container {
font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
max-width: 600px;
margin: 20px auto;
padding: 25px;
border: 1px solid #e0e0e0;
border-radius: 10px;
background-color: #f9f9f9;
box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
color: #333;
}
.bmi-calculator-container h2 {
text-align: center;
color: #2c3e50;
margin-bottom: 25px;
font-size: 1.8em;
}
.bmi-calculator-container .input-group {
margin-bottom: 18px;
display: flex;
flex-direction: column;
}
.bmi-calculator-container label {
display: block;
margin-bottom: 8px;
font-weight: bold;
color: #555;
font-size: 1em;
}
.bmi-calculator-container input[type="number"],
.bmi-calculator-container select {
width: calc(100% – 20px);
padding: 12px;
border: 1px solid #ccc;
border-radius: 6px;
font-size: 1em;
box-sizing: border-box;
transition: border-color 0.3s ease;
}
.bmi-calculator-container input[type="number"]:focus,
.bmi-calculator-container select:focus {
border-color: #007bff;
outline: none;
box-shadow: 0 0 0 2px rgba(0, 123, 255, 0.25);
}
.bmi-calculator-container .radio-group {
margin-bottom: 20px;
display: flex;
gap: 20px;
align-items: center;
}
.bmi-calculator-container .radio-group label {
font-weight: normal;
margin-bottom: 0;
display: flex;
align-items: center;
cursor: pointer;
}
.bmi-calculator-container .radio-group input[type="radio"] {
margin-right: 8px;
transform: scale(1.2);
}
.bmi-calculator-container button {
width: 100%;
padding: 14px;
background-color: #007bff;
color: white;
border: none;
border-radius: 6px;
font-size: 1.1em;
font-weight: bold;
cursor: pointer;
transition: background-color 0.3s ease, transform 0.2s ease;
margin-top: 10px;
}
.bmi-calculator-container button:hover {
background-color: #0056b3;
transform: translateY(-2px);
}
.bmi-calculator-container #result {
margin-top: 25px;
padding: 18px;
border: 1px solid #d4edda;
background-color: #e9f7ef;
border-radius: 6px;
font-size: 1.1em;
font-weight: bold;
color: #155724;
text-align: center;
min-height: 50px;
display: flex;
align-items: center;
justify-content: center;
line-height: 1.5;
}
.bmi-calculator-container #result.error {
border-color: #f5c6cb;
background-color: #f8d7da;
color: #721c24;
}
.bmi-calculator-container .unit-specific-input {
display: flex;
gap: 10px;
}
.bmi-calculator-container .unit-specific-input .input-group {
flex: 1;
margin-bottom: 0;
}
.bmi-calculator-container .unit-specific-input .input-group label {
margin-bottom: 8px;
}
.bmi-calculator-container .unit-specific-input .input-group input {
width: calc(100% – 20px);
}
.bmi-calculator-container .article-content {
margin-top: 30px;
line-height: 1.6;
color: #444;
font-size: 0.95em;
}
.bmi-calculator-container .article-content h3 {
color: #2c3e50;
margin-top: 25px;
margin-bottom: 15px;
font-size: 1.4em;
}
.bmi-calculator-container .article-content p {
margin-bottom: 15px;
}
.bmi-calculator-container .article-content ul {
list-style-type: disc;
margin-left: 20px;
margin-bottom: 15px;
}
.bmi-calculator-container .article-content li {
margin-bottom: 8px;
}
function toggleUnits() {
var metricInputs = document.getElementById('metricInputs');
var imperialInputs = document.getElementById('imperialInputs');
var unitSystem = document.querySelector('input[name="unitSystem"]:checked').value;
if (unitSystem === 'metric') {
metricInputs.style.display = 'block';
imperialInputs.style.display = 'none';
} else {
metricInputs.style.display = 'none';
imperialInputs.style.display = 'block';
}
// Clear previous results
document.getElementById('result').innerHTML = 'Enter your details and click \'Calculate BMI\'.';
document.getElementById('result').classList.remove('error');
}
function calculateBMI() {
var unitSystem = document.querySelector('input[name="unitSystem"]:checked').value;
var weight, height, bmi;
var resultDiv = document.getElementById('result');
resultDiv.classList.remove('error');
if (unitSystem === 'metric') {
weight = parseFloat(document.getElementById('weightKg').value);
height = parseFloat(document.getElementById('heightCm').value);
if (isNaN(weight) || isNaN(height) || weight <= 0 || height <= 0) {
resultDiv.innerHTML = 'Please enter valid positive numbers for weight and height.';
resultDiv.classList.add('error');
return;
}
// Convert height from cm to meters
var heightMeters = height / 100;
bmi = weight / (heightMeters * heightMeters);
} else { // Imperial
weight = parseFloat(document.getElementById('weightLbs').value);
var heightFt = parseFloat(document.getElementById('heightFt').value);
var heightIn = parseFloat(document.getElementById('heightIn').value);
if (isNaN(weight) || isNaN(heightFt) || isNaN(heightIn) || weight <= 0 || (heightFt <= 0 && heightIn <= 0)) {
resultDiv.innerHTML = 'Please enter valid positive numbers for weight and height.';
resultDiv.classList.add('error');
return;
}
// Convert feet and inches to total inches
var totalInches = (heightFt * 12) + heightIn;
bmi = (weight / (totalInches * totalInches)) * 703;
}
var bmiCategory = '';
if (bmi = 18.5 && bmi = 25.0 && bmi <= 29.9) {
bmiCategory = 'Overweight';
} else {
bmiCategory = 'Obesity';
}
resultDiv.innerHTML = 'Your BMI is: ' + bmi.toFixed(2) + 'Category: ' + bmiCategory + '';
}
// Initialize units on page load
window.onload = toggleUnits;
BMI Calculator
Enter your details and click 'Calculate BMI'.
Understanding Your Body Mass Index (BMI)
The Body Mass Index (BMI) is a simple numerical measure that is commonly used to classify whether a person is underweight, normal weight, overweight, or obese. It's a widely accepted screening tool for potential weight problems for adults, but it does not diagnose body fatness or health of an individual.
How is BMI Calculated?
The BMI is calculated using a person's weight and height. There are two primary formulas depending on the unit system used:
- Metric Formula: BMI = weight (kg) / (height (m))^2
- Imperial Formula: BMI = (weight (lbs) / (height (inches))^2) * 703
Our calculator allows you to easily switch between these two systems to get your BMI.
BMI Categories for Adults (20 years and older):
- Underweight: Less than 18.5
- Normal weight: 18.5 – 24.9
- Overweight: 25.0 – 29.9
- Obesity: 30.0 or greater
These categories are standard for most adults. For children and teens, BMI is interpreted differently, taking age and sex into account.
Limitations of BMI
While BMI is a useful screening tool, it has limitations:
- Muscle Mass: Athletes or very muscular individuals may have a high BMI without being overweight because muscle weighs more than fat.
- Body Composition: BMI doesn't distinguish between fat mass and lean mass.
- Age and Sex: BMI ranges don't account for differences in body composition due to age or sex (e.g., older adults may have more body fat at a lower BMI).
- Ethnicity: Different ethnic groups may have different healthy BMI ranges.
Therefore, BMI should be used as a general guide. For a comprehensive assessment of your health, it's always best to consult with a healthcare professional who can consider other factors like waist circumference, body fat percentage, diet, and physical activity levels.
Using This BMI Calculator
To use this calculator, simply select your preferred unit system (Metric or Imperial), enter your weight and height in the respective fields, and click 'Calculate BMI'. The result will instantly show your BMI value and its corresponding category, helping you get a quick understanding of where you stand.