BMI Calculator
Calculate your Body Mass Index (BMI) instantly. Toggle between metric and imperial units
to find out if your weight is in a healthy range.
What Is BMI?
Body Mass Index (BMI) is a widely used measure that estimates body fat based on your height
and weight. It is calculated by dividing your weight in kilograms by the square of your height
in meters (kg/m²). While BMI does not measure body fat directly, it correlates with more
direct measures and is a quick screening tool for weight categories that may lead to health problems.
BMI Categories
The World Health Organization defines four main BMI categories: Underweight (below 18.5),
Normal weight (18.5–24.9), Overweight (25–29.9), and Obese (30 and above). These ranges
apply to adults aged 20 and older. Children and teens use age-specific percentile charts instead.
A normal BMI suggests a lower risk of weight-related health conditions like heart disease,
type 2 diabetes, and high blood pressure.
Limitations of BMI
BMI is a useful starting point, but it has limitations. It does not distinguish between muscle
and fat — a muscular athlete may have a high BMI but low body fat. Similarly, older adults
who have lost muscle mass may show a normal BMI despite carrying excess fat. For a complete
picture of your health, consider consulting a healthcare professional who can assess body
composition, waist circumference, and other risk factors alongside BMI.
What Is BMI and How Is It Calculated?
Body Mass Index (BMI) is a simple measure that uses your height and weight to estimate whether you're underweight, normal weight, overweight, or obese. The formula divides your weight in kilograms by the square of your height in meters (kg/m²). Our calculator supports both metric and imperial units.
Understanding Your BMI Results
The World Health Organization classifies BMI as: Underweight (below 18.5), Normal weight (18.5–24.9), Overweight (25–29.9), and Obese (30+). While BMI is a useful screening tool, it doesn't account for muscle mass, bone density, age, or gender. Athletes and muscular individuals may have a high BMI without excess body fat.
This calculator runs entirely in your browser. Your health data stays private — nothing is stored or transmitted.