About the BMI Calculator
Body Mass Index (BMI) is a widely used screening measurement that estimates whether a person's weight is in a healthy range relative to their height, calculated with a simple formula from just two numbers. This calculator computes your BMI instantly and shows which standard weight category it falls into, supporting both metric and imperial units.
This tool is useful for anyone tracking general health metrics at home, healthcare-adjacent professionals needing a quick reference calculation, and students learning about this common (though limited) health screening measurement.
To use it, choose metric (kilograms and centimeters) or imperial (pounds and inches/feet) units, enter your height and weight, and your BMI is calculated instantly using the standard formula (weight in kilograms divided by height in meters squared). The result is shown alongside the standard World Health Organization weight categories: underweight, normal weight, overweight, and obese.
For example, someone who is 170cm tall and weighs 65kg has a BMI of approximately 22.5, which falls within the "normal weight" range (18.5–24.9) according to standard WHO categories — a quick, simple way to get a general sense of where your weight falls relative to established population-level ranges.
A critical limitation to understand is that BMI is a population-level screening tool, not a precise individual health diagnosis — it doesn't distinguish between muscle mass and fat mass, meaning very muscular individuals (like athletes and bodybuilders) often show a "overweight" or "obese" BMI despite having low body fat and excellent health, since muscle is denser than fat. Similarly, BMI doesn't account for factors like age, sex, bone density, or where fat is distributed on the body, all of which meaningfully affect actual health risk. Because of these well-documented limitations, BMI should be treated as one general, easy-to-calculate reference point rather than a definitive individual health assessment — always discuss your specific health status with a qualified healthcare provider who can consider your complete individual context rather than relying on BMI alone.
Tip: if you're an athlete, very muscular, pregnant, elderly, or otherwise fall outside the general population BMI was originally studied on, treat your BMI result with extra caution and prioritize other health indicators (like body composition, fitness level, and bloodwork) discussed with a healthcare professional over this single simplified number.