Weight and Height Calculator

Body Mass Index (BMI) Calculator

Select your preferred unit system:

Enter your details and click "Calculate BMI" to see your result.

function toggleUnits() { var metricInputs = document.getElementById("metricInputs"); var imperialInputs = document.getElementById("imperialInputs"); var unitMetric = document.getElementById("unitMetric"); if (unitMetric.checked) { metricInputs.style.display = "block"; imperialInputs.style.display = "none"; } else { metricInputs.style.display = "none"; imperialInputs.style.display = "block"; } } function calculateBMI() { var bmi; var category; var unitMetric = document.getElementById("unitMetric").checked; var resultDiv = document.getElementById("bmiResult"); if (unitMetric) { // Metric calculation var weightKg = parseFloat(document.getElementById("weightKg").value); var heightCm = parseFloat(document.getElementById("heightCm").value); if (isNaN(weightKg) || isNaN(heightCm) || weightKg <= 0 || heightCm <= 0) { resultDiv.style.backgroundColor = "#f8d7da"; resultDiv.style.borderColor = "#f5c6cb"; resultDiv.style.color = "#721c24"; resultDiv.innerHTML = "Please enter valid positive numbers for weight (kg) and height (cm)."; return; } var heightM = heightCm / 100; bmi = weightKg / (heightM * heightM); } else { // Imperial calculation var weightLbs = parseFloat(document.getElementById("weightLbs").value); var heightFeet = parseFloat(document.getElementById("heightFeet").value); var heightInches = parseFloat(document.getElementById("heightInches").value); if (isNaN(weightLbs) || isNaN(heightFeet) || isNaN(heightInches) || weightLbs <= 0 || (heightFeet <= 0 && heightInches <= 0)) { resultDiv.style.backgroundColor = "#f8d7da"; resultDiv.style.borderColor = "#f5c6cb"; resultDiv.style.color = "#721c24"; resultDiv.innerHTML = "Please enter valid positive numbers for weight (lbs) and height (feet/inches)."; return; } var totalInches = (heightFeet * 12) + heightInches; bmi = (weightLbs / (totalInches * totalInches)) * 703; } // Determine BMI category if (bmi = 18.5 && bmi = 25 && bmi < 29.9) { category = "Overweight"; resultDiv.style.backgroundColor = "#fff3cd"; // Yellowish for caution resultDiv.style.borderColor = "#ffeeba"; resultDiv.style.color = "#856404"; } else { category = "Obese"; resultDiv.style.backgroundColor = "#f8d7da"; // Reddish for warning resultDiv.style.borderColor = "#f5c6cb"; resultDiv.style.color = "#721c24"; } resultDiv.innerHTML = "Your BMI is: " + bmi.toFixed(2) + ". This falls into the " + category + " category."; }

Understanding Your Body Mass Index (BMI)

The Body Mass Index (BMI) is a widely used screening tool that helps assess whether a person has a healthy body weight in proportion to their height. It's a simple calculation that provides a quick estimate of body fat and can indicate potential health risks associated with being underweight, overweight, or obese.

How is BMI Calculated?

The BMI calculation uses a straightforward formula based on your weight and height. There are two primary formulas depending on the unit system you use:

Metric Formula:

If you use kilograms (kg) for weight and centimeters (cm) for height, the formula is:

BMI = Weight (kg) / (Height (m) × Height (m))

To use this, you first convert your height from centimeters to meters by dividing by 100. For example, if you weigh 70 kg and are 175 cm (1.75 m) tall:

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

Imperial Formula:

If you use pounds (lbs) for weight and inches (in) for height, the formula is:

BMI = (Weight (lbs) / (Height (inches) × Height (inches))) × 703

For example, if you weigh 150 lbs and are 5 feet 9 inches (69 inches) tall:

BMI = (150 / (69 * 69)) * 703 = (150 / 4761) * 703 ≈ 0.0315 * 703 ≈ 22.15

BMI Categories: What Your Number Means

Once your BMI is calculated, it falls into one of several categories, indicating your weight status:

• Underweight: BMI less than 18.5
• Normal or Healthy Weight: BMI 18.5 to 24.9
• Overweight: BMI 25.0 to 29.9
• Obese: BMI 30.0 or higher

These categories are general guidelines and are used by health professionals to assess potential health risks.

Why is BMI Important?

Maintaining a healthy BMI is crucial for overall well-being. Individuals with a high BMI (overweight or obese) are at an increased risk for various health conditions, including:

• Heart disease and stroke
• Type 2 diabetes
• High blood pressure (hypertension)
• Certain types of cancer
• Sleep apnea
• Osteoarthritis

Conversely, being underweight can also lead to health issues such as malnutrition, weakened immune system, osteoporosis, and fertility problems.

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 categorizing them as overweight or obese.
• Body Composition: It doesn't account for body fat distribution. For example, abdominal fat carries higher health risks than fat stored in the hips and thighs.
• Age and Sex: BMI interpretations can vary for children, adolescents, and older adults. It also doesn't account for differences in body composition between sexes.
• Ethnicity: Different ethnic groups may have varying healthy BMI ranges.

Therefore, BMI should be used as a general indicator and not as the sole determinant of health. Other factors like waist circumference, body fat percentage, diet, physical activity levels, and family history are also crucial for a comprehensive health assessment.

Using the Calculator

To use our BMI calculator, simply:

1. Select your preferred unit system (Metric or Imperial).
2. Enter your weight and height in the respective fields.
3. Click the "Calculate BMI" button.

Your BMI and its corresponding category will be displayed instantly.

Disclaimer: This BMI calculator is intended for informational purposes only and should not be used as a substitute for professional medical advice. Always consult with a healthcare provider for personalized health assessments and recommendations.