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Body Mass Index (BMI) Calculator

Use this calculator to determine your Body Mass Index (BMI) and understand your weight category based on standard classifications.

function calculateBMI() { var weightKg = parseFloat(document.getElementById("weightKg").value); var heightCm = parseFloat(document.getElementById("heightCm").value); var resultDiv = document.getElementById("bmiResult"); if (isNaN(weightKg) || isNaN(heightCm) || weightKg <= 0 || heightCm <= 0) { resultDiv.innerHTML = "Please enter valid positive numbers for weight and height."; return; } var heightM = heightCm / 100; // Convert cm to meters var bmi = weightKg / (heightM * heightM); var bmiCategory = ""; var advice = ""; if (bmi = 18.5 && bmi = 25 && bmi < 29.9) { bmiCategory = "Overweight"; advice = "Being overweight can increase the risk of certain health conditions. Lifestyle changes may be beneficial."; } else { bmiCategory = "Obese"; advice = "Obesity significantly increases the risk of various health problems. It's recommended to consult a healthcare professional for guidance."; } resultDiv.innerHTML = "

Your BMI: " + bmi.toFixed(2) + "

" + "Category: " + bmiCategory + "" + "" + advice + ""; } .bmi-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: 600px; margin: 30px auto; border: 1px solid #e0e0e0; } .bmi-calculator-container h2 { color: #333; text-align: center; margin-bottom: 20px; font-size: 28px; } .bmi-calculator-container p { color: #555; line-height: 1.6; margin-bottom: 15px; } .calculator-form .form-group { margin-bottom: 18px; } .calculator-form label { display: block; margin-bottom: 8px; color: #444; font-weight: bold; font-size: 16px; } .calculator-form input[type="number"] { width: calc(100% – 22px); padding: 12px; border: 1px solid #ccc; border-radius: 6px; font-size: 16px; box-sizing: border-box; transition: border-color 0.3s ease; } .calculator-form input[type="number"]:focus { border-color: #007bff; outline: none; box-shadow: 0 0 5px rgba(0, 123, 255, 0.2); } .calculator-form button { background-color: #007bff; color: white; padding: 12px 25px; border: none; border-radius: 6px; cursor: pointer; font-size: 18px; font-weight: bold; display: block; width: 100%; margin-top: 25px; transition: background-color 0.3s ease, transform 0.2s ease; } .calculator-form button:hover { background-color: #0056b3; transform: translateY(-2px); } .calculator-result { margin-top: 30px; padding: 20px; background-color: #e9f7ef; border: 1px solid #d4edda; border-radius: 8px; color: #155724; font-size: 17px; line-height: 1.6; } .calculator-result h3 { color: #0f5132; margin-top: 0; font-size: 24px; margin-bottom: 10px; } .calculator-result p { margin-bottom: 8px; }

Understanding Your Body Mass Index (BMI)

The Body Mass Index (BMI) is a simple numerical measure that is commonly used to classify whether an individual's weight is healthy in relation to their height. It's a widely adopted screening tool for potential weight problems for adults, but it does not diagnose body fatness or health of an individual.

How is BMI Calculated?

BMI is calculated using a straightforward formula that takes into account your weight and height. The formula is:

BMI = weight (kg) / [height (m)]2

For example, if you weigh 70 kilograms and are 1.75 meters tall, your BMI would be calculated as:

BMI = 70 / (1.75 * 1.75) = 70 / 3.0625 = 22.86

This calculation provides a single number that can then be compared against standard BMI categories.

BMI Categories for Adults

For adults aged 20 and older, BMI is interpreted using standard weight status categories:

• Underweight: Less than 18.5
• Normal weight: 18.5 – 24.9
• Overweight: 25.0 – 29.9
• Obese: 30.0 or greater

These categories provide a general guide to assess an individual's weight status.

Limitations of BMI

While BMI is a useful screening tool, it's important to understand its limitations:

• Muscle Mass: BMI does not distinguish between muscle and fat. Athletes or individuals with high muscle mass may have a high BMI but very little body fat, incorrectly classifying them as overweight or obese.
• Age and Sex: BMI interpretations can vary with age and sex, though the standard categories are generally applied to adults.
• Body Composition: It doesn't account for body fat distribution. For instance, abdominal fat is considered a higher health risk than fat distributed elsewhere.
• Ethnicity: Some ethnic groups may have different health risks at different BMI ranges.
• Individual Differences: BMI is a population-level measure and may not accurately reflect the health status of every individual.

Why Use a BMI Calculator?

A BMI calculator offers a quick and easy way to get a general idea of your weight status. It can be a starting point for discussions with healthcare professionals about your weight and overall health. While not a definitive diagnostic tool, it serves as a valuable indicator for identifying potential weight-related health risks.

Important Disclaimer

The information provided by this BMI calculator is for general informational purposes only and should not be considered medical advice. Always consult with a qualified healthcare professional for personalized advice regarding your weight, diet, exercise, and any health concerns you may have.