Am I Fat? BMI Calculator
Use this calculator to determine your Body Mass Index (BMI) and understand if your weight falls into a healthy category for your height.
.calculator-container {
font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
background-color: #f9f9f9;
padding: 25px;
border-radius: 10px;
box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
max-width: 700px;
margin: 30px auto;
border: 1px solid #e0e0e0;
}
.calculator-container h2 {
color: #333;
text-align: center;
margin-bottom: 20px;
font-size: 28px;
}
.calculator-container p {
color: #555;
text-align: center;
margin-bottom: 25px;
line-height: 1.6;
}
.calculator-form .input-group {
margin-bottom: 18px;
display: flex;
flex-wrap: wrap;
align-items: center;
}
.calculator-form .input-group label {
flex: 1 1 120px;
color: #444;
font-weight: bold;
margin-right: 15px;
font-size: 16px;
}
.calculator-form .input-group input[type="number"] {
flex: 2 1 200px;
padding: 12px;
border: 1px solid #ccc;
border-radius: 6px;
font-size: 16px;
transition: border-color 0.3s ease;
}
.calculator-form .input-group input[type="number"]:focus {
border-color: #007bff;
outline: none;
box-shadow: 0 0 0 3px rgba(0, 123, 255, 0.25);
}
.calculator-form .input-group input[type="radio"] {
margin-right: 8px;
transform: scale(1.1);
}
.calculator-form .input-group label[for="metric"],
.calculator-form .input-group label[for="imperial"] {
flex: 0 0 auto;
margin-right: 20px;
font-weight: normal;
color: #555;
}
.calculator-container button {
display: block;
width: 100%;
padding: 14px 20px;
background-color: #007bff;
color: white;
border: none;
border-radius: 6px;
font-size: 18px;
font-weight: bold;
cursor: pointer;
transition: background-color 0.3s ease, transform 0.2s ease;
margin-top: 25px;
}
.calculator-container button:hover {
background-color: #0056b3;
transform: translateY(-2px);
}
.calculator-result {
margin-top: 30px;
padding: 20px;
background-color: #e9f7ff;
border: 1px solid #cce5ff;
border-radius: 8px;
font-size: 18px;
color: #333;
text-align: center;
line-height: 1.8;
}
.calculator-result strong {
color: #0056b3;
font-size: 22px;
}
.calculator-result .bmi-category {
font-weight: bold;
margin-top: 10px;
font-size: 20px;
}
.bmi-category.underweight { color: #ffc107; } /* Yellow */
.bmi-category.normal { color: #28a745; } /* Green */
.bmi-category.overweight { color: #fd7e14; } /* Orange */
.bmi-category.obese { color: #dc3545; } /* Red */
@media (max-width: 600px) {
.calculator-form .input-group label {
flex: 1 1 100%;
margin-bottom: 8px;
}
.calculator-form .input-group input[type="number"] {
flex: 1 1 100%;
}
.calculator-form .input-group label[for="metric"],
.calculator-form .input-group label[for="imperial"] {
margin-right: 10px;
}
}
function updateUnitLabels() {
var metricRadio = document.getElementById('metric');
var weightUnitLabel = document.getElementById('weightUnitLabel');
var heightUnitLabel = document.getElementById('heightUnitLabel');
var weightInput = document.getElementById('weightInput');
var heightInput = document.getElementById('heightInput');
if (metricRadio.checked) {
weightUnitLabel.textContent = 'kg';
heightUnitLabel.textContent = 'cm';
weightInput.placeholder = 'e.g., 70';
heightInput.placeholder = 'e.g., 175';
} else {
weightUnitLabel.textContent = 'lbs';
heightUnitLabel.textContent = 'inches';
weightInput.placeholder = 'e.g., 154';
heightInput.placeholder = 'e.g., 69';
}
}
function calculateBMI() {
var weightInput = document.getElementById('weightInput');
var heightInput = document.getElementById('heightInput');
var bmiResultDiv = document.getElementById('bmiResult');
var metricRadio = document.getElementById('metric');
var weight = parseFloat(weightInput.value);
var height = parseFloat(heightInput.value);
if (isNaN(weight) || isNaN(height) || weight <= 0 || height <= 0) {
bmiResultDiv.innerHTML = 'Please enter valid positive numbers for both weight and height.';
return;
}
var bmi;
var weight_kg;
var height_m;
if (metricRadio.checked) {
weight_kg = weight; // Weight is already in kg
height_m = height / 100; // Convert cm to meters
} else {
weight_kg = weight * 0.453592; // Convert lbs to kg
height_m = height * 0.0254; // Convert inches to meters
}
if (height_m === 0) { // Prevent division by zero
bmiResultDiv.innerHTML = 'Height cannot be zero.';
return;
}
bmi = weight_kg / (height_m * height_m);
var bmiRounded = bmi.toFixed(1);
var category = '';
var categoryClass = '';
var advice = '';
if (bmi = 18.5 && bmi = 25 && bmi = 30
category = 'Obese';
categoryClass = 'obese';
advice = 'Obesity significantly increases the risk of serious health conditions. It is highly recommended to seek guidance from a healthcare professional for weight management.';
}
bmiResultDiv.innerHTML =
'Your BMI is:
' + bmiRounded + '' +
'Category: ' + category + " +
" + advice + ";
}
// Initialize labels on page load
window.onload = updateUnitLabels;
Understanding Your Body Mass Index (BMI)
The "Am I Fat?" calculator uses a widely accepted metric called the Body Mass Index (BMI) to assess whether your weight is healthy in proportion to your height. While it's a simple and useful screening tool, it's important to understand what BMI is, how it's calculated, and its limitations.
What is BMI?
BMI is a numerical value derived from your weight and height. It's used to categorize individuals into different weight status groups: underweight, normal weight, overweight, and obese. It serves as an indicator of body fatness for most people and can be a screening tool for weight categories that may lead to health problems.
How is BMI Calculated?
The formula for BMI is:
- Metric System: BMI = weight (kg) / [height (m)]2
- Imperial System: BMI = [weight (lbs) / height (inches)2] x 703
Our calculator handles these conversions automatically based on your chosen measurement system, providing you with an accurate BMI value.
BMI Categories and What They Mean
Once your BMI is calculated, it falls into one of the following categories:
- Underweight: BMI less than 18.5
- Normal Weight: BMI between 18.5 and 24.9
- Overweight: BMI between 25 and 29.9
- Obese: BMI of 30 or greater
These categories are general guidelines. For example, a BMI of 22.5 would indicate a normal weight, while a BMI of 28.0 would suggest being overweight.
Limitations of BMI
While BMI is a good general indicator, it has limitations and doesn't tell the whole story about your health:
- Muscle Mass: Athletes or individuals with high muscle mass may have a high BMI without being "fat" because muscle weighs more than fat. Their BMI might categorize them as overweight or obese, even if their body fat percentage is low.
- Body Composition: BMI doesn't distinguish between fat mass and lean mass. Two people with the same BMI could have very different body compositions.
- Age and Gender: BMI interpretations can vary slightly with age and gender, though the standard categories are widely applied.
- Ethnicity: Some ethnic groups may have different health risks at different BMI ranges.
- Fat Distribution: Where fat is stored on the body (e.g., around the waist vs. hips) can be a better indicator of health risk than BMI alone.
Beyond BMI: When to Consult a Professional
BMI is a screening tool, not a diagnostic tool. If your BMI falls outside the "normal weight" range, or if you have concerns about your weight, body composition, or overall health, it's always best to consult a healthcare professional. They can perform further assessments, such as measuring body fat percentage, waist circumference, and evaluating your diet, physical activity levels, and medical history, to provide a comprehensive understanding of your health status and personalized recommendations.
Remember, a healthy lifestyle involves more than just a number on a scale or a BMI calculation. It encompasses balanced nutrition, regular physical activity, adequate sleep, and stress management.