Assess your weight category using the Body Mass Index (BMI) formula.
Kilograms (kg)
Pounds (lbs)
Centimeters (cm)
Meters (m)
Inches (in)
Feet (ft)
Your BMI is: —
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Understanding Body Mass Index (BMI)
The Body Mass Index (BMI) is a numerical value derived from the mass (weight) and height of an individual. It serves as a widely used screening tool to categorize a person's weight status relative to their height, helping to identify potential weight categories that may increase the risk of certain health problems. It's important to remember that BMI is a general indicator and does not directly measure body fat or overall health.
How is BMI Calculated?
The standard formula for calculating BMI is:
BMI = weight (kg) / [height (m)]2
In this calculator, we handle conversions for different units of weight and height to ensure an accurate BMI calculation.
If your weight is in pounds (lbs) and height in inches (in), the formula is: BMI = [weight (lbs) / (height (in))2] * 703.
If your weight is in pounds (lbs) and height in feet (ft), first convert feet to inches (1 ft = 12 in), then use the formula above.
If your weight is in kilograms (kg) and height in centimeters (cm), first convert centimeters to meters (1 m = 100 cm), then use the standard formula.
BMI Categories
The World Health Organization (WHO) and other health organizations use the following standard BMI ranges:
Underweight: BMI less than 18.5
Normal weight: BMI from 18.5 to 24.9
Overweight: BMI from 25 to 29.9
Obese: BMI 30 or greater
Each category has different implications for health risks. For instance, being underweight can be associated with nutritional deficiencies, while being overweight or obese increases the risk of conditions like heart disease, type 2 diabetes, and certain cancers.
Who Should Use a BMI Calculator?
A BMI calculator is a useful tool for:
Individuals looking to understand their general weight status.
People interested in tracking changes in their weight relative to their height.
Healthcare professionals as an initial screening tool.
Limitations of BMI
It is crucial to acknowledge that BMI has limitations:
It does not distinguish between muscle mass and fat mass. Athletes or very muscular individuals may have a high BMI but low body fat.
It does not account for fat distribution, which can be an important factor in health risks.
It may not be as accurate for certain populations, such as the elderly or pregnant women.
Therefore, BMI should always be considered alongside other health indicators and discussed with a healthcare provider for a comprehensive assessment of your health and well-being.
function calculateBMI() {
var weightInput = document.getElementById("weight");
var weightUnit = document.getElementById("weightUnit").value;
var heightInput = document.getElementById("height");
var heightUnit = document.getElementById("heightUnit").value;
var weight = parseFloat(weightInput.value);
var height = parseFloat(heightInput.value);
if (isNaN(weight) || isNaN(height) || weight <= 0 || height <= 0) {
alert("Please enter valid positive numbers for weight and height.");
return;
}
var weightKg = weight;
if (weightUnit === "lbs") {
weightKg = weight * 0.453592;
}
var heightM = height;
if (heightUnit === "cm") {
heightM = height / 100;
} else if (heightUnit === "in") {
heightM = height * 0.0254;
} else if (heightUnit === "ft") {
heightM = height * 12 * 0.0254;
}
if (heightM <= 0) {
alert("Height in meters must be a positive value.");
return;
}
var bmi = weightKg / (heightM * heightM);
bmi = parseFloat(bmi.toFixed(1)); // Round to one decimal place
var bmiCategory = "";
var bmiValueElement = document.getElementById("bmiValue");
var bmiCategoryElement = document.getElementById("bmiCategory");
var resultDiv = document.getElementById("result");
bmiValueElement.textContent = bmi;
if (bmi = 18.5 && bmi = 25 && bmi <= 29.9) {
bmiCategory = "Overweight";
bmiCategoryElement.className = "result-category highlight-overweight";
} else {
bmiCategory = "Obese";
bmiCategoryElement.className = "result-category highlight-obese";
}
bmiCategoryElement.textContent = "(" + bmiCategory + ")";
resultDiv.style.display = "block";
}