body {
font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
background-color: #f8f9fa;
color: #333;
line-height: 1.6;
margin: 0;
padding: 20px;
}
.bmi-calc-container {
max-width: 800px;
margin: 40px auto;
background-color: #ffffff;
padding: 30px;
border-radius: 8px;
box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
border: 1px solid #e0e0e0;
}
h1 {
color: #004a99;
text-align: center;
margin-bottom: 30px;
border-bottom: 2px solid #004a99;
padding-bottom: 10px;
}
.input-group {
margin-bottom: 20px;
display: flex;
flex-direction: column;
align-items: flex-start;
}
.input-group label {
display: block;
margin-bottom: 8px;
font-weight: 500;
color: #004a99;
}
.input-group input[type="number"] {
width: 100%;
padding: 12px;
border: 1px solid #ccc;
border-radius: 4px;
box-sizing: border-box;
font-size: 1rem;
}
button {
background-color: #004a99;
color: white;
padding: 12px 25px;
border: none;
border-radius: 4px;
cursor: pointer;
font-size: 1.1rem;
transition: background-color 0.3s ease;
width: 100%;
margin-top: 10px;
}
button:hover {
background-color: #003366;
}
#result {
margin-top: 30px;
padding: 20px;
background-color: #e9ecef;
border: 1px solid #dee2e6;
border-radius: 5px;
text-align: center;
}
#result h2 {
color: #004a99;
margin-top: 0;
}
#bmiValue {
font-size: 2.5rem;
font-weight: bold;
color: #004a99;
}
#bmiCategory {
font-size: 1.4rem;
font-weight: bold;
margin-top: 10px;
color: #28a745; /* Default to green, will change based on category */
}
.result-details {
margin-top: 15px;
font-size: 0.95rem;
color: #555;
}
.article-section {
margin-top: 40px;
padding-top: 30px;
border-top: 1px solid #eee;
}
.article-section h2 {
color: #004a99;
margin-bottom: 15px;
}
.article-section p, .article-section ul, .article-section li {
margin-bottom: 15px;
}
.article-section ul {
list-style-type: disc;
margin-left: 20px;
}
@media (max-width: 768px) {
.bmi-calc-container {
padding: 20px;
}
button {
font-size: 1rem;
padding: 10px 20px;
}
#bmiValue {
font-size: 2rem;
}
#bmiCategory {
font-size: 1.2rem;
}
}
Understanding Body Mass Index (BMI)
Body Mass Index (BMI) is a simple, inexpensive, and noninvasive screening tool that categorizes a person's weight in relation to their height. It is used as an indicator of potential weight categories that may lead to health problems. A higher or lower BMI than the normal range can be an indicator of health risks.
The BMI Formula
The standard formula for calculating BMI is:
BMI = weight (kg) / [height (m)]²
Since this calculator uses height in centimeters (cm), the formula is adjusted:
BMI = weight (kg) / [ (height (cm) / 100) ]²
Or more simply:
BMI = (weight (kg) * 10000) / [height (cm)]²
For example, if a person weighs 70 kg and is 175 cm tall:
Height in meters = 175 cm / 100 = 1.75 m
BMI = 70 kg / (1.75 m * 1.75 m) = 70 / 3.0625 ≈ 22.86
Using the cm formula:
BMI = (70 * 10000) / (175 * 175) = 700000 / 30625 ≈ 22.86
Interpreting Your BMI
The World Health Organization (WHO) and other health organizations use the following general categories for BMI values in adults:
- Underweight: Less than 18.5
- Normal weight: 18.5 to 24.9
- Overweight: 25 to 29.9
- Obesity: 30 or greater
It's important to note that BMI is a screening tool and does not diagnose body fatness or health. Factors like muscle mass, bone density, and body composition can affect BMI. For a comprehensive assessment of your health and weight, consult with a healthcare professional.
Who Should Use This Calculator?
This calculator is useful for individuals seeking a quick assessment of their weight status based on standard international units (kilograms and centimeters). It's a common tool for:
- General health awareness
- Tracking weight management progress
- Understanding potential health risks associated with weight
- Fitness enthusiasts and athletes (though BMI may be less accurate for very muscular individuals)
function calculateBMI() {
var weight = parseFloat(document.getElementById("weight").value);
var height = parseFloat(document.getElementById("height").value);
var resultDiv = document.getElementById("result");
var bmiValueDiv = document.getElementById("bmiValue");
var bmiCategoryDiv = document.getElementById("bmiCategory");
if (isNaN(weight) || isNaN(height) || weight <= 0 || height <= 0) {
alert("Please enter valid numbers for weight and height.");
resultDiv.style.display = 'none';
return;
}
var heightInMeters = height / 100;
var bmi = weight / (heightInMeters * heightInMeters);
bmi = bmi.toFixed(2); // Round to two decimal places
var category = "";
var categoryColor = "#28a745"; // Default to green
if (bmi = 18.5 && bmi = 25 && bmi <= 29.9) {
category = "Overweight";
categoryColor = "#fd7e14"; // Orange for overweight
} else {
category = "Obesity";
categoryColor = "#dc3545"; // Red for obesity
}
bmiValueDiv.textContent = bmi;
bmiCategoryDiv.textContent = category;
bmiCategoryDiv.style.color = categoryColor;
resultDiv.style.display = 'block';
}