Calculate your Body Mass Index (BMI) to understand your weight category.
Your BMI Results
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What is Body Mass Index (BMI)?
Body Mass Index (BMI) is a simple calculation that uses your weight and height to estimate how much body fat you have. It's a widely used screening tool that can help indicate the weight categories that may lead to health problems. A high BMI may indicate that you are overweight, and a low BMI may indicate that you are underweight.
How is BMI Calculated?
The formula for BMI is straightforward. It is calculated by dividing your weight in kilograms by the square of your height in meters. If you prefer to use imperial units, you can divide your weight in pounds by your height in inches squared, and then multiply the result by a conversion factor of 703.
Formula (Metric): BMI = weight (kg) / (height (m))^2
Since the calculator asks for height in centimeters, we first convert it to meters by dividing by 100.
Example Calculation:
If a person weighs 70 kg and is 175 cm tall:
Convert height to meters: 175 cm / 100 = 1.75 m
Calculate BMI: 70 kg / (1.75 m * 1.75 m) = 70 / 3.0625 = 22.86
Therefore, the BMI is approximately 22.86.
Understanding Your BMI Score
The BMI score is then compared to a standard range to categorize your weight. These categories are generally accepted guidelines, but it's important to remember that BMI does not directly measure body fat and doesn't account for muscle mass, bone density, or body composition. Therefore, it's best used as a starting point for discussion with a healthcare professional.
Standard BMI Categories:
Underweight: BMI less than 18.5
Normal weight: BMI 18.5 to 24.9
Overweight: BMI 25 to 29.9
Obesity: BMI 30 or greater
For example, a BMI of 22.86 falls into the "Normal weight" category. A BMI of 31.5 would be considered "Obesity," and a BMI of 17.0 would be "Underweight."
Use Cases for the BMI Calculator
The BMI calculator is a valuable tool for individuals seeking to:
Gain a general understanding of their current weight status.
Track changes in their weight over time and assess the impact on their BMI.
Set realistic weight goals in consultation with healthcare providers.
Educate themselves about weight-related health risks.
It's crucial to consult with a doctor or registered dietitian for personalized health advice, especially if you have any underlying health conditions or are considering significant changes to your diet or exercise routine.
function calculateBMI() {
var weightKg = parseFloat(document.getElementById("weightKg").value);
var heightCm = parseFloat(document.getElementById("heightCm").value);
var resultDiv = document.getElementById("result");
var bmiValueSpan = document.getElementById("bmiValue");
var bmiCategorySpan = document.getElementById("bmiCategory");
// Clear previous results
bmiValueSpan.textContent = "-";
bmiCategorySpan.textContent = "-";
resultDiv.style.borderColor = "#ced4da"; // Reset border color
// Validate inputs
if (isNaN(weightKg) || isNaN(heightCm) || weightKg <= 0 || heightCm <= 0) {
bmiCategorySpan.textContent = "Please enter valid positive numbers for weight and height.";
bmiCategorySpan.style.color = "#dc3545"; // Red for error
resultDiv.style.borderColor = "#dc3545";
return;
}
// Convert height from cm to meters
var heightM = heightCm / 100;
// Calculate BMI
var bmi = weightKg / (heightM * heightM);
// Round BMI to two decimal places
var roundedBmi = bmi.toFixed(2);
var category = "";
var categoryColor = "#28a745"; // Default to success green
// Determine BMI category
if (bmi = 18.5 && bmi = 25 && bmi = 30
category = "Obesity";
categoryColor = "#dc3545"; // Danger red
}
// Display results
bmiValueSpan.textContent = roundedBmi;
bmiCategorySpan.textContent = "Category: " + category;
bmiCategorySpan.style.color = categoryColor;
resultDiv.style.borderColor = categoryColor; // Match result border to category color
}