Calculate your Body Mass Index and determine your weight category.
Your Body Mass Index (BMI) is:
0.0
Normal
Understanding Your BMI Results
Body Mass Index (BMI) is a simple numerical measure of a person's thickness or thinness based on their height and weight. It is widely used as a general indicator of whether a person has a healthy body weight for their height.
BMI Category Table
BMI Range
Category
Less than 18.5
Underweight
18.5 – 24.9
Normal weight
25.0 – 29.9
Overweight
30.0 or more
Obesity
How the BMI Formula Works
The calculation uses the standard metric formula: Weight (kg) / [Height (m)]². For example, if a person weighs 70kg and is 175cm (1.75m) tall, the calculation is 70 / (1.75 * 1.75) = 22.86 BMI.
Why BMI Matters
Maintaining a BMI within the "Normal" range is associated with a lower risk of several health conditions, including:
Type 2 Diabetes
Hypertension (High Blood Pressure)
Cardiovascular Disease
Certain types of cancers
Sleep Apnea
Is BMI Always Accurate?
While the BMI calculator is a helpful screening tool, it has limitations. It does not directly measure body fat and does not account for muscle mass, bone density, or overall body composition. For instance, athletes or bodybuilders may have a high BMI due to increased muscle mass rather than high body fat.
function calculateBMI() {
var weight = parseFloat(document.getElementById('weight_input').value);
var height = parseFloat(document.getElementById('height_input').value);
var resultBox = document.getElementById('bmi_result_box');
var bmiValueDisplay = document.getElementById('bmi_value');
var bmiCategoryDisplay = document.getElementById('bmi_category');
var bmiDescription = document.getElementById('bmi_description');
if (isNaN(weight) || isNaN(height) || weight <= 0 || height <= 0) {
alert("Please enter valid positive numbers for weight and height.");
return;
}
// BMI Formula: weight (kg) / [height (m)]^2
var heightInMeters = height / 100;
var bmi = weight / (heightInMeters * heightInMeters);
var roundedBMI = bmi.toFixed(1);
bmiValueDisplay.innerText = roundedBMI;
resultBox.style.display = 'block';
var category = "";
var color = "";
var description = "";
if (bmi = 18.5 && bmi = 25 && bmi <= 29.9) {
category = "Overweight";
color = "#f39c12";
description = "You are in the overweight category. This may increase your risk for certain health issues. Consider lifestyle changes to manage your weight.";
} else {
category = "Obesity";
color = "#e74c3c";
description = "Your BMI falls within the obese range. This is associated with higher health risks. We recommend speaking with a doctor about weight management.";
}
bmiCategoryDisplay.innerText = category;
bmiCategoryDisplay.style.color = color;
bmiValueDisplay.style.color = color;
resultBox.style.borderColor = color;
bmiDescription.innerText = description;
// Scroll result into view
resultBox.scrollIntoView({ behavior: 'smooth', block: 'nearest' });
}